Desperate for advice on replacing dead 255K BTU furnace in 3200 sq foot house

[magichappens]

9 months ago, I put my entire life savings into the down payment for a home (built in 1955) in the Oakland Hills (northern california)

My fiancé and I recently found out that our monstrous 50 year old 255K BTU furnace (70% efficiency in its day) has cracks in 4 out of 6 of the heat exchangers and was emitting carbon monoxide (yikes!). They no longer make residential furnaces of that size, so deciding how to replace it has been an exercise in frustration and confusion. We have gotten 5 separate estimates, all providing vastly different opinions as to what should be done to replace our furnace and adequately and most efficiently heat our home. How is one to know who to trust and believe? My head is spinning from all of the different advice we've been given (which I'll detail further down in this post)

To complicate things further, our home was custom built by the previous owner, and has a very unique open floor plan on the upstairs level, which constitutes about 2600 sq feet of the home. There are 11 registers and 2 large returns on the upstairs level (although both my office and our dining room have NO registers and we've been told they can't be added). The downstairs level accounts for approximately 600 square feet and contains our family room (which has a single register in it)and a guest bedroom with no registers in it.

The entire length of the house, on both levels, has floor to ceiling windows facing south that provide a breathtaking panoramic view of the bay. However, they are older windows, with metal frames, and are very inefficient -- the house loses a lot of heat when it is cold through those windows, yet when the sun is out the vast southern exposure beams through the house, heating it sometimes to the point where I literally feel like a dog locked in a car on a hot summer day. We are in the hills, and it can get windy, meaning it can get super cold at night. Yet when the sun is shining, it actually heats up to the point that by mid-afternoon I'm opening windows because it's too warm -- even in November (although once the rainy season starts it will be cold all the time -- I know this from our first month in the house, last February, wherein we got a $550 PG&E bill that almost gave me a heart attack...

-- after that I had tried not running the heat, but even with wool sweaters my fingers were still too cold to type and you can't operate a touchpad with gloves on..)

We have a home warranty, which should cover the cost of replacing the furnace, although it turns out that the list of uncovered items is much larger than what is covered.. The home warranty sent out Company A to provide an estimate for the furnace replacement. They came back with the suggestion of replacing our 70% efficient 255K BTU furnace with an

80% 100K BTU furnace to the tune of $6300, $2100 of which we would have to pay out of pocket. As we were shocked both by the price, and by the size of the unit they were suggesting (how could this adequately heat our home?), I did a little researching on the Better Business Bureau website and found Company A had several unresolved complaints filed against them. Not good.

I decided to get some estimates of my own, and had 3 separate companies come out to the house. Companies B & C each suggested getting a single 80% efficiency 155K BTU unit. However, we were concerned whether even this would provide adequate heating AND we were informed both by the home warranty company and by Company E (who provided estimate number 5 as a 2nd opinion on behalf of the home warranty company) that it is illegal to install a furnace larger than

125K BTU in a residential home in California. Is this true? If so, I'm even more bewildered as to who to trust, as Company C is Sears - a brand I thought was highly reputable.

Then there was Company D, which is a member of the BBB, has no complaints filed against them, and is also an authorized installer for Home Depot. This company provided the most thorough examination of our home and took into account the materials it was made of, the layout, and all of the windows, in addition to the square footage, in making their recommedation. They suggested getting two seperate 80% efficient 100K BTU furnaces and using a "twinning kit" to make the units operate as one, providing a total of 200K BTU to heat the home. In addition to seem the most knowledgable of the contractors thus far, they also had worked with our home warranty company in the past (and is only no longer on the list of approved contractors b/c they didn't send their latest proof of insurance over, which they are now doing so that we might be able to have the home warranty company authorize their doing the repairs)

When we called the home warranty company and told them of Company D's recommendations, the home warranty rep who answered told us that twinning is not a proper furnace installation, and could actually cause our home to blow up! The home warranty company said they wanted to send another company out of their choice for a 2nd opinion (the abovementioned Company E).

When Company E showed up, they told us they would recommend putting in two 80% efficient 90K BTU units -- that were twinned! We told them what the home warranty company said about twinning, and they said that was inaccurate and that they did twinning systems all the time and it was the only way to heat a home of our size, and that the same home warranty company had previously authorized such repairs in the past.

Yet when we next spoke with the home warranty company, we found out that Company E had actually sent in a completely different job estimate to them, with recommendations of a zoned system with a single 125K 80% efficient BTU unit for the upstairs, and a 75K 80% eff. unit for the downstairs. As such, there would be extensive ductwork modification that would need to be done to zone the system, leaving us with almost $2900 in uncovered costs.

(thanks for your patience if you're still reading this far!)

By this point I felt like my head was spinning, and could not understand why the contractor who came to our home would tell us they would be installing 2 twinned 90K BTU units, only to then send an estimate to the home warranty company for an entirely different job. The home warranty rep suggested I call Copmany E and ask why there was a discrepancy between what they'd told us and what they told the home warranty company, and to explain why they'd want to do a zoned system over a twinned system.

I'm already beyond 'house poor', so if I'm going to be spending this much money I want to know that the job will be done right, that the house won't "blow up", and that we will actually have enough heat for our home (particularly the upstairs level)

So I called Company E, and was told that the estimater said he thought it would be more efficient to do the zoned system. When I expressed my concern as to whether the single 125k BTU unit could really heat the

2600 sq foot open floor plan windows everywhere upstairs of the house, which had 11 registers, not to mention the fact that the downstairs level only has a single register and no returns I was told they'd have to call the guy who did the estimate and then get back to me. They later called me back and said "Yeah, he said you could do it as twinned". I then asked why did he submit it as being a zoned system to the home warranty company, to which I didn't really get an adequate response. I also could not get an adequate answer over which would actually be the better choice for my home, but that if I went with the twinning it would only save me $235 for the install of a second thermostat (how can that be? wouldn't all the extra ductwork modification needed for zoning drop the price down if the system were twinned?)

I am looking to cut costs b/c I'm pretty broke right now, but not at the expense of safety, comfort level, or decreasing the value of the house by not getting the right furnace installed. Meanwhile we have no heat, and I've no idea which (if any) of these contractors I can trust.

This is my first home, and I've been told by numerous friends who have been homeowners for far longer that it is *very* difficult to find a good HVAC contractor - and of course, no one had any they could recommend. I feel like I just don't have enough information to possibly make a decision as to whether to go with a twinned system, or a zoned system, which contractor to choose, etc.

I literally am desperate for some advice from those who are more knowledgable regarding heating issues. TIA for the help, and also for having gotten this far in my huge rambling anxious post!!!

[Stretch]

I do very little gas any more as I live in Heat Pump country now. Your old furnace sounds way too big. The proper size is determined by doing a "Load Calculation" that takes into account YOUR weather conditions, window sizes type and directions, door area, wall area, ceiling area, floor area and insulation levels for all those things. This involves following ACCA Manual J, usually with a computer program.

The air flow should be measured to determine if your present ducts are sized properly.

When I lived in Pennsylvania, we had no trouble twinning furnaces on large houses. Some furnaces had twinning kits available.

The thing about California law saying 125 K is max furnace size sounds goofy, but, hey, you five in the goofiest state in the USA.

If you send me your email address with spaces around the "at" and "dot" I will email you an article on high efficiency installations, which should save you money in the long run.

Kevin O'Neill "Stretch"

843-385-2220 O'Neill Bagwell Cooling & Heating Myrtle Beach, SC

[m Ransley]

So you have 2600 sq ft in Ca where its not that cold and you think you need 200k btu or so, Im no pro but you need a written load calculation done on the house to know what you need in Btu. Did anyone do one? So you might have been oversized and may still be. Im in zone 5 to -20f

1800sqft on a windy lake and was calculated to need 50k btu on a super insulated house. I actualy only need my 47000btu 1st stage, never the 78000 second stage. One thing you need new windows and probably insulation, I would ask for a copy of the written load calc all these pros did [sure] and go with the smallest unit you can. And look into new glass, and figure that into your unit size if you can afford it. You are loosing winter and summer without Low E argon glass, with the heat up you describe you likely have regular glass.

[Al Moran]

Go with company d. As for the "twinning", while Iv'e never actually seen a setup like this, I see systems every day ( Sacramento area) that have a twin connection on the integrated furnace control board so someone must be doing it. Reasearch the local codes for your area regarding this.

Make sure that whatever company you hire does a "manual J" calculation and a "manual D" calculation. Manual J is for sizing the unit based on windows, how many, what type, which way they face, trees and shading over the house, how well the house is insulated, square footage of rooms, are interior walls insulated, etc. Manual D is for duct sizing. Duct sizing is very important to getting the proper air flow to each room.

Stay away from any company that does not answer all of your questions to your satisfaction.

[hvacturtle]

This is Turtle.

As I read your post here i see you have orginized mass confussion forming here and also have seen a mass amount of bullshit reported to you. So here is some info that you can use so far.

Twinning of furnaces is nothing but making two furnaces turn off and on together as one unit. like 2 -- 100K BTU would become 1 -- 200K BTU furnace.

Now Being informed that you have to replace a 255 k btu furnce on a house that you bought less than 1 years ago. Louisiana law says if you buy a house through a realestate dealer. that Dealer will have to fix anything that was not disclosed in the closing papers for 1 year. I know california is different from Louisiana law but you may look into it.

Dealing with a Home insurance company to deal with on repairs is one of the hardest thing in the world to get done. I see you have the bill of $6,300.00 and your going to have to pay $2,100.00 of it. this is 1/3 of the bill and it sounds like the insurance company is sending you to school. You must be getting this policy dirty cheap for that percent of the lost that you will have to pay.

these words of not twinning furnaces on residentiual furnaces sounds like bullshit to me. i have twinned furnace on residentiual application for a many a year and have no words said about not doing it.

i see your getting a bunch of bull by tring to please a contract and a insurance company all at one time. You have to get with A hvac contractor and decide on what is to be done and then call the insurance company and talk to them.

Now Picking a HVAC contractor. Have him show you his contractor licences and proof of contractor liability for the area, Ask for referrences and phone numbers and names to call, He will have to run a heat load on the house & discuss it with you or don't send me a bid, and last of all have him talk to you and not your insurance company for deciding the quality of the job. The insurance company is tring to cut the cost and the quality of the job down and your tring to get the quality up on it.

Now don't deal with any contracxtor that does not answser all your question in a timely manner.

If you like E-Mail me and discuss it.

TURTLE

[Tim Fischer]

2600 was the "upper level". He also mentioned 600sqft on the "lower level". Not sure if that makes the house 3200sqft, or if there's other areas not mentioned...

Still, 3200sqft at 200+kbtu in Cali seems like WAY overkill. We have

2700sqft in Minnesota and our current unit (circa 1980) has a whopping 63kbu. And I'm guessing you don't see many 20-degree-below-zero days in Cali -- we usually see some every year.

-Tim

[buffalobill]

you need some sleep.

got a gas kitchen stove? crack open a window a few inches and turn it on to bake 500, leaving the oven door closed to protect the safety pilot.

got an ELECTRIC clothes dryer? disconnect its exhaust flex and point it into the house, set for timed dry, maximum minutes, maximum temperature. push start

now the pipes can't freeze if you keep them warm at the fixture rooms such as the bathroom, so plug in some digital thermostat portable electric heaters, they will throw off 1500 watts of heat.

here's the seasonal averages. pretty nice.

an 80,000btu forced air furnace costs under $600. plus parts and ducts and pipe and labor.

got wind? put up a windmill.

you need an attorney or insurance adjuster to deal with the insurance company. once you get that money in your hand you can make your own deal for the systems you want.

you need to refinance your expensive home with a home equity loan and have some home repair lines of credit available to you.

every system failure has a silver lining, you're being firmly pushed into the future savings of energy star.

now that the house is warmed up, read all this:

this

you need to put your utility company on balanced billing so there are no surprises in winter.

[Richard J Kinch]

Quite the essay you have written. That you have a home (non-)warranty, and faith in the BBB as a quality detector, shows that you have much to learn. Those two things are prime indicators for "sucker". But my hunch is, you got suckered on the house itself.

Offhand it sounds like you need to renovate with a zoned hot water system.

A different house might be simpler and cheaper, if the process was informed by some critical thinking.

[nicksanspam]

wrote re:

My Canyon (2 miles from Oakland) CA friends don't believe in insulation, nor anything else in the building codes :-)

.... 255K Btu PER HOUR seems like a lot. NREL says 1050 Btu/ft^2 of sun falls on a south wall on an average 48.7 F January day in San Francisco with a 55.6 daily max. ASHRAE's 99% winter design temp is 35 F, ie it's warmer 99% of the time. Solar house heating is _extremely easy_ in SF.

Trust and believe me. Stretch and Turtle are OK, but orthodox. SQlit is dogmatic, mransley sometimes acts like an arrogant idiot, Meehan and Radwinski could learn more about heatflow, and so on.

.... 255K Btu/h for 3200 ft^2? Does this house have walls? :-) You probably need a blower door test and more insulation.

Lovely :-)

That's OK in CA. A square foot of R1 south window with 90% solar transmission would gain 0.9x1050 = 945 Btu on an average January day. On a 24-hour living space, it might lose 24h(65-48.7)1ft^2/R1 = 391 with a net gain of 554. On a low-thermal mass sunspace, it might lose 6h(70-52) = 108, netting 837.

Congratulations! You have a solar-heated house! It needs more thermal mass, maybe upstairs or below the ceiling, with an insulated wall between all those windows and the 24-hour living space and airflow between the new "sunspace" and the living space that stops at night.

You might "open windows" with a thermostat and an exhaust fan...

NREL says 830 Btu/ft^2 of sun falls on a south wall on an average 52.2 F February day in San Francisco with a 60.8 daily max. A square foot of R1 south window would gain 0.9x830 = 747 Btu and lose 24h(65-52.2)1ft^2/R1 = 307, for a net gain of 440. On a low-thermal mass sunspace, it might lose 6h(70-56.5) = 81, for a net evil gain of 666 on an average Feb day.

My advice: forswear thy fossil fuels and improve the solar performance. It's easy, with high-school physics and simple arithmetic.

Nick

[m Ransley]

A few things others noted, the BBB is a joke for you to put any faith into. Your prices quoted are sounding very high for what you are being offered. I don`t know your total heating bill for a year but you say 550 for a month of feb. Figure how much your actual yearly heating bill was. There are high efficiency condensing furnaces which are the norm here and do save alot more than an 80% unit. Different manufacturers have different efficiency ratings , they go from apx 93% to a new unit that has 97%. The savings difference is figured on the differential of the 2 units. A 97% will save you 21% over an 80%, not 17% as many think . I personaly would not consider an 80% unit unless yearly heating was only a few hundred. You say Feb was 550 so im guessing 400 was heat so you qualify for high efficiency condensing unit, and that was at last years Ng prices, not todays or in 5 years, my prices are up 70% this year.

You state no ducts can be run to 2 rooms, I find that real hard to believe that something can`t be done as I have just upgraded a 110 yr home without heat in 3 rooms. Flex duct for "Spacepack AC" is run everyday to retrofit old homes and can be enginered to do heat, Ive done it for a hard to plumb room. With a house of that size you are forgetting VS DC zoneable systems that will save 25-50% in running the blower. They are available on the best condensing units and can remove

50% more humidity in summer and give more even winter heat through slower fan operation.

For 2900 Im getting a Carrier infinity 94% with VSDC and special thermostat instaled, your price of 6300 for 80% units sounds extremely excessive.

You had a few unqualified bids that did no load calculation as I see it ranging from 100k Btu to 200k Btu. 100k btu 80% efficient gives out 80k Btu heat. 200k outputs 160k Btu. At 96% efficiency 100k outputs 96k Btu and 200k outputs 192k btu. A 20% increase meaning a 20% smaller unit is needed. A great difference in output you should consider in sizing is output and their efficiency.

For probably under 4000$ you could get a 97% VSDC out putting 120000 btu that is equivilant to a 80% 144000 input unit and save winter and summer through its VS DC motor. With some insulation even this unit would be oversized for your area.

You need to learn about what you need and what is offered and run some real numbers on utility, equipment, costs and paybacks. Run the numbers with todays higher Ng costs and double it for 10 years, then you will realy see that an 80%er is dumb.

You only need the unit sized to keep you warm on the coldest days running 24hrs a day, If you are going to keep the place future insulating will make the difference. Caulking everything will reduce wind iniltration. Insulating curtains and Cellular shades can take the R

1 windows you have to R 5- 6+ likely that would reduce your Btu needed by a very great amount. If you can do it figure the load calc several ways for true sizing needed. I sized and had my AC instaled before I knew this or insulated, so I regret im oversized and humid. There are many sites on heating, windows, insulation you need to learn as your "heating pros" are not helping you they are just instalers. Im no pro but in zone 5 1800 sq I paid 465 last year for Ng down from 2000 by doing my own research and following my ideas, not any salesmans.

[m Ransley]

Yea you trust nick and his math, I trust facts and hands on experiance of pros.

[Bill]

I certainly understand your situation... It took everything I had to buy my house. So been there, done that!

It sounds to me like heating your house is going keep you "broke" from now until eternity!

So I would look at this long term - what is best in the long range of things?

I think energy rates are going to keep going up, up, up. So I think the thing to do would be to eventually install double pane "Energy Star" argon filled windows in your house. This will *drastically* reduce your heating and air conditioning costs. And also you should eventually insulate the heck out of your house.

But this will cost a lot of money, and if you are constantly paying high heating and air conditioning bills, you may never have the money to make the improvements...

So what I would do for now is to get the largest heating unit you can get, and zone the house out. Instead of heating the *entire* house, figure out which rooms or which portion of the house can be heated while leaving the rest of the house unheated. (Close doors.) Perhaps you can move your office elsewhere for the time being?

Then just heat certain rooms or a certain section of the house. This will save you money on energy bills for the time being. Then maybe you could have one window replaced a year with an "Energy Star" window - this will be expensive. Eventually when all windows are replaced and the home is well insulated, your heating requirements will be much less.

Then you should be able to heat your entire home for a more reasonable cost. And at that time, you will not need such a large monster furnace!

Here is the Energy Star web site...

[House]

FYI I have a 3600SQ feet house + finished basement in Toronto, were it is much colder than N. California. Last year I replaced 120,000BTU gas forced air furnace with 100,000BUT High Efficiency furnace and it is more than enough to keep my house worm. Is you attic insulated?

9 months ago, I put my entire life savings into the down payment for a home (built in 1955) in the Oakland Hills (northern california)

My fiancé and I recently found out that our monstrous 50 year old 255K BTU furnace (70% efficiency in its day) has cracks in 4 out of 6 of the heat exchangers and was emitting carbon monoxide (yikes!). They no longer make residential furnaces of that size, so deciding how to replace it has been an exercise in frustration and confusion. We have gotten 5 separate estimates, all providing vastly different opinions as to what should be done to replace our furnace and adequately and most efficiently heat our home. How is one to know who to trust and believe? My head is spinning from all of the different advice we've been given (which I'll detail further down in this post)

To complicate things further, our home was custom built by the previous owner, and has a very unique open floor plan on the upstairs level, which constitutes about 2600 sq feet of the home. There are 11 registers and 2 large returns on the upstairs level (although both my office and our dining room have NO registers and we've been told they can't be added). The downstairs level accounts for approximately 600 square feet and contains our family room (which has a single register in it)and a guest bedroom with no registers in it.

The entire length of the house, on both levels, has floor to ceiling windows facing south that provide a breathtaking panoramic view of the bay. However, they are older windows, with metal frames, and are very inefficient -- the house loses a lot of heat when it is cold through those windows, yet when the sun is out the vast southern exposure beams through the house, heating it sometimes to the point where I literally feel like a dog locked in a car on a hot summer day. We are in the hills, and it can get windy, meaning it can get super cold at night. Yet when the sun is shining, it actually heats up to the point that by mid-afternoon I'm opening windows because it's too warm -- even in November (although once the rainy season starts it will be cold all the time -- I know this from our first month in the house, last February, wherein we got a $550 PG&E bill that almost gave me a heart attack...

-- after that I had tried not running the heat, but even with wool sweaters my fingers were still too cold to type and you can't operate a touchpad with gloves on..)

We have a home warranty, which should cover the cost of replacing the furnace, although it turns out that the list of uncovered items is much larger than what is covered.. The home warranty sent out Company A to provide an estimate for the furnace replacement. They came back with the suggestion of replacing our 70% efficient 255K BTU furnace with an

80% 100K BTU furnace to the tune of $6300, $2100 of which we would have to pay out of pocket. As we were shocked both by the price, and by the size of the unit they were suggesting (how could this adequately heat our home?), I did a little researching on the Better Business Bureau website and found Company A had several unresolved complaints filed against them. Not good.

I decided to get some estimates of my own, and had 3 separate companies come out to the house. Companies B & C each suggested getting a single 80% efficiency 155K BTU unit. However, we were concerned whether even this would provide adequate heating AND we were informed both by the home warranty company and by Company E (who provided estimate number 5 as a 2nd opinion on behalf of the home warranty company) that it is illegal to install a furnace larger than

125K BTU in a residential home in California. Is this true? If so, I'm even more bewildered as to who to trust, as Company C is Sears - a brand I thought was highly reputable.

Then there was Company D, which is a member of the BBB, has no complaints filed against them, and is also an authorized installer for Home Depot. This company provided the most thorough examination of our home and took into account the materials it was made of, the layout, and all of the windows, in addition to the square footage, in making their recommedation. They suggested getting two seperate 80% efficient 100K BTU furnaces and using a "twinning kit" to make the units operate as one, providing a total of 200K BTU to heat the home. In addition to seem the most knowledgable of the contractors thus far, they also had worked with our home warranty company in the past (and is only no longer on the list of approved contractors b/c they didn't send their latest proof of insurance over, which they are now doing so that we might be able to have the home warranty company authorize their doing the repairs)

When we called the home warranty company and told them of Company D's recommendations, the home warranty rep who answered told us that twinning is not a proper furnace installation, and could actually cause our home to blow up! The home warranty company said they wanted to send another company out of their choice for a 2nd opinion (the abovementioned Company E).

When Company E showed up, they told us they would recommend putting in two 80% efficient 90K BTU units -- that were twinned! We told them what the home warranty company said about twinning, and they said that was inaccurate and that they did twinning systems all the time and it was the only way to heat a home of our size, and that the same home warranty company had previously authorized such repairs in the past.

Yet when we next spoke with the home warranty company, we found out that Company E had actually sent in a completely different job estimate to them, with recommendations of a zoned system with a single 125K 80% efficient BTU unit for the upstairs, and a 75K 80% eff. unit for the downstairs. As such, there would be extensive ductwork modification that would need to be done to zone the system, leaving us with almost $2900 in uncovered costs.

(thanks for your patience if you're still reading this far!)

By this point I felt like my head was spinning, and could not understand why the contractor who came to our home would tell us they would be installing 2 twinned 90K BTU units, only to then send an estimate to the home warranty company for an entirely different job. The home warranty rep suggested I call Copmany E and ask why there was a discrepancy between what they'd told us and what they told the home warranty company, and to explain why they'd want to do a zoned system over a twinned system.

I'm already beyond 'house poor', so if I'm going to be spending this much money I want to know that the job will be done right, that the house won't "blow up", and that we will actually have enough heat for our home (particularly the upstairs level)

So I called Company E, and was told that the estimater said he thought it would be more efficient to do the zoned system. When I expressed my concern as to whether the single 125k BTU unit could really heat the

2600 sq foot open floor plan windows everywhere upstairs of the house, which had 11 registers, not to mention the fact that the downstairs level only has a single register and no returns I was told they'd have to call the guy who did the estimate and then get back to me. They later called me back and said "Yeah, he said you could do it as twinned". I then asked why did he submit it as being a zoned system to the home warranty company, to which I didn't really get an adequate response. I also could not get an adequate answer over which would actually be the better choice for my home, but that if I went with the twinning it would only save me $235 for the install of a second thermostat (how can that be? wouldn't all the extra ductwork modification needed for zoning drop the price down if the system were twinned?)

I am looking to cut costs b/c I'm pretty broke right now, but not at the expense of safety, comfort level, or decreasing the value of the house by not getting the right furnace installed. Meanwhile we have no heat, and I've no idea which (if any) of these contractors I can trust.

This is my first home, and I've been told by numerous friends who have been homeowners for far longer that it is *very* difficult to find a good HVAC contractor - and of course, no one had any they could recommend. I feel like I just don't have enough information to possibly make a decision as to whether to go with a twinned system, or a zoned system, which contractor to choose, etc.

I literally am desperate for some advice from those who are more knowledgable regarding heating issues. TIA for the help, and also for having gotten this far in my huge rambling anxious post!!!

[modervador]

He's probably right. Your situation sounds like a good fit for zoning.

You probably lack qualification to determine whether 11 registers has anything to do with 125kBTU, but they should be able to give you an answer if you ask the right questions. They proposed to rework the ductwork anyway, right? That means they're already seriously thinking about the air balance and heating needs of the two zones.

The answer doesn't match the question. Are you sure your question didn't mention twinning or whether it could be done cheaper with a single zone?

The communications between you and the estimator are "filtered" by the guy on the phone. Chances are good that's where your problem is in getting adequate response. He might be asking the estimator the question he thinks you're trying to ask, and giving you the answer he thinks you want to hear. Ask to speak directly with the estimator if you can.

Here's what I think happened. The estimator told you his initial impressions upon seeing the system you already had and ballpark guestimating by the total square footage of your building. After closer inspection and further consideration of your unique building, he determined that you'd be better off with zoning and with certain deficiencies corrected. So they provided their recommendation to the warranty company for what you should really get done.

I'm going to guess that your questions give the impression that you're looking to save costs, so they're offering you a cheaper but less optimum alternative.

You have only one register and no return on the first floor? Offhand, it does not sound like your ductwork is appropriate, but I can't see it from here. It could be that most of the ductwork modification is to provide some to the first floor, which you may need in either case.

If you have two stories, generally the better choice for comfort and energy efficiency is zoned. When you bring costs of installation and upkeep into the picture, comfort and energy are traded for dollars. For some, a single zone is "comfortable enough" and "efficient enough" not to justify the added expense of zoning.

I think contractor E sounds more "with it" except for the communication problems, which let's face it might be at least partially on your end of the phone. It's tough to be an educated consumer untill you've already consumed a bit ;-)

[modervador]

Installing "the largest heating unit you can get" and then closing off registers to keep some rooms unheated is a good way to decrease the lifespan and efficiency of the furnace, making your wallet much lighter in the long run.

The furnace must be sized for the particulars of the zone(s) it feeds. If it is desired to have part of the house colder than another, they should be on separate zones by design.

[Iain McClatchie]

For folks who don't know the Bay Area, Canyon, CA is a famous place. Check it out:

It's the green spot between Pinehurst Rd and Shephard Canyon Rd, right in the middle where it looks like there are almost no roads. If this guy's got a view of the bay, then he's probably on the south-west side of Manzanita Way.

Decades ago, a bunch of people decided to build there against the official wishes of Oakland. They build houses and I think even short roads, completely without city support. I think they're on-grid now, after decades of wrangling, but maybe not.

Anyway, I just wanted Nick to know that just from riding around in the area I can say it gets a *lot* colder there at night than it does in San Francisco. This guy probably has a monster furnace because that was cheaper than insulation back when the house was slapped together.

Nick> Solar house heating is _extremely easy_ in SF.

Solar house heating *during the day* is easy near SF. It's the nights that get you. This guy's probably got 800+ ft^2 of glass and probably sees days of 20+ degree-days heating. That's

400k BTUs a night just through the glass, he might have to double that for the total (tons of fresh air). The furnace is just a bit oversize for such a leaky house, but the house is a bad design in an environment of pricey fuel.

And thermal storage is hard. Note that this guy is sitting more-or-less on top of the Hayward fault, probably on a sloping lot with poor footings, and probably has fairly weak construction. Placing a few dozen tons of thermal mass on the second floor, nevermind the ceiling, would be irresponsible (although very much in character for the neighborhood).

If he's seriously lucky, he's got room on the north side of the house for some thermal storage, maybe even a basement cut into the hill with a floor that can take some load. If that's the case, maybe he could get some sort of loop going between the downstairs storage area on the north side and the upstairs southern living space.

Nick> ... 255K Btu/h for 3200 ft^2? Does this house have walls? Nick> :-) You probably need a blower door test and more Nick> insulation.

Yep. That could make a serious dent in about half the problem. But that glass is going to be expensive to replace. If he's near broke, I think it might be reasonable to consider insulation against the glass at night. Ugly, inconvenient, and cheap.

Nick> Congratulations! You have a solar-heated house! It needs Nick> more thermal mass, maybe upstairs or below the ceiling, Nick> with an insulated wall between all those windows and the Nick> 24-hour living space and airflow between the new Nick> "sunspace" and the living space that stops at night.

Your low-mass sunspace is probably a nonstarter, as it would mean he has to give up a sizeable fraction of the house for all but ten hours of the day (and most of those hours he's not home during the weekdays). My guess is he's got the master bedroom on the south side as well.

Nick> You might "open windows" with a thermostat and an Nick> exhaust fan...

Yep.

OP> I am looking to cut costs b/c I'm pretty broke right now, OP> but not at the expense of safety, comfort level, or OP> decreasing the value of the house by not getting the OP> right furnace installed. Meanwhile we have no heat, OP> and I've no idea which (if any) of these contractors I OP> can trust.

Nick> My advice: forswear thy fossil fuels and improve the Nick> solar performance. It's easy, with high-school physics Nick> and simple arithmetic.

Thermal storage will cost a lot more than a bigger furnace and burning more fuel, especially in the short term.

My advice:

1) More insulation, especially attic insulation. 2) Blower test, and then patch those leaks. This could lead to getting a new door or something, but hopefully it's just weathersealing. PG&E might pay for the blower test. 3) Thermostat-controlled exhaust fan, for those hot days. 4) Insulation on the windows at night. This is ugly, but maybe you could do something creative like have interior shutters that hinge down from the ceiling with a drawstring. The insulation could be 2 inch thick extruded polystyrene slabs covered in cloth to make them look nice, and also to help get a reasonably airtight fit between the insulation and the window frame when deployed. This could save 2-3 therms ($3-5) per night, if you're disciplined about getting those shutters down every night before you go to bed. 5) Sweaters.

A big furnace is going to be cheaper than thermal storage. My wild guess is that you're now burning 1500 therms/year for heating. You can probably get that down to 600-700 therms/year without thermal storage, assuming the window insulation. So that says you can probably get away with a half-size furnace, maybe 100k BTU/hr. The money you save versus a replacement 225k BTU/hr furnace might offset most of the cost of the insulation updates.

[HeatMan]

Some furnaces don't need a twinning kit, just a single communication wire..

[Iain McClatchie]

Nick> You might "open windows" with a thermostat and an exhaust fan...

If I'm right about that 800 ft^2 of glass, and if 400 ft^2 of it is passing sunlight, then he's getting 332k BTU on those February days you quoted. While the sun is up, he'll lose 50k BTU through the windows. Assuming he loses a good chunk elsewhere and has no significant thermal storage he'll need to vent over 1000 cfm at 80F (from outside

55F). Not exactly an 8" NuTone bathroom fan.

Nick> My advice: forswear thy fossil fuels and improve the solar Nick> performance. It's easy, with high-school physics and simple Nick> arithmetic.

....and many, many tons of water.

[nicksanspam]

.... 400 ft^2 of single glass might pass 0.9x250x400 = 90K Btu/h in full sun.

.... and lose (70-56.5)400/R1 = 5.4K Btu/h.

.... Significant improvements are possible.

.... cfm = (90K-5.4K)/(80-55) = 3384, approximately. With your command of numbers, you might consider a different preoccupation, eg surgery :-)

Maybe 3 $12 20" window box fans, if he wanted to waste all that solar heat. Or 2 $55 2470 cfm Lasko fans, or a single whole house fan.

With enough insulation, it wouldn't need any water, nor windows.

A 32' R32 cube with no air infiltration would need 24h(65-48.7)5x32^2/32 = 62.6K Btu on an average Jan day in SF. It might come from 18.3 kWh/day or 550 kWh/mo of internal electrical usage, 2/3 of the 833 US average.

With no internal heat gain, it might stay warm for 5 cloudy days with

5x62.6K/(130-80)/2000 = 3.13 tons of water cooling from 130 to 80 F in a 3.13x2000/1024/62.33x12 = 1.2" layer under the 4th floor ceiling. If A ft^2 of R1 sunspace glazing with 90% solar transmission over the R32 south wall gains 945A Btu/day and loses 6h(130-56.5)A = 441A and makes 62.6K Btu net, A = 124 ft^2, eg an 8'x16' sunspace or $200 patch of polycarbonate solar siding.

Solar house heating is extremely easy in San Francisco.

Nick

[nicksanspam]

The 1st floor ceiling would be better, with less insulation above it and less heat loss to the outdoors.

ie 945A - 441A = 62.6K makes A = 124 ft^2.

Nick