Propane and electric pump heat questions

Hi,

I live in the Boston area and am currently considering purchasing a house that has a combination of electric pump heat and propane heat. Most of the houses I've lived in and seen in the area use either gas or oil heat, so I wanted to get some opinions from the group regarding these other types of home heating systems.

To provide a little more detail, this house was originally built in the 80s with an electric heat pump. The owners installed a Rinnai based propane system about 5 years ago to reduce their heating costs. The Rinnai system is set up with propane tanks outside the house and 5 standing heating units around the house. Two of these units are downstairs, two are in bedrooms upstairs, and one is in the basement. Each of the heating units has its own thermostat. The house is large, about 3500 square feet. There is no gas line to this house

My principle questions are around:

  1. Can anyone comment on the electric heat pump? Boston gets fairly cold and I've heard that these systems don't work well in very cold weather.

  1. Can anyone comment on Rinnai direct-vent heating systems? I've never seen them around and wonder if there's a good reason for that. Are they efficient? Are they safe? Is it safe to have big propane tanks next to the house? What do I need to know here?

  2. Presumably, I could install an oil based furnace if I wanted. Any sense for how much something like that costs? Can oil based systems do forced hot air, using the duct system that the electric pump already has in place?

I've also asked for historic heating/electricity bills. It looks like propane bills are $2000/year and electricity is about $4000/year. This seems high to me, but obviously it's dependent on what the owner's heat needs have been.

Appreciate any thoughts or comments... My initial thought is to walk away from this, largely because I don't understand the systems and don't like uncertainty. But I thought I'd get opinions from the group to see if there are different thoughts.

Thanks, PB

Reply to
PB2
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I have the opposite; a propane furnace with electric HVAC in a 2 story addition. I like the balance, My fuel use is necessarily less in Texas, & heat pumps work well here at least until it dips below 30, then emergency heat kicks in at a lot more $ per hr. I think this is what the previous owner had in mind, just something to keep the heating coils from kicking on. I could see how this could be managed to not eat you out of house and home; set the unused rooms back to say

55 degrees & only bump them up when using them, lock out the emergency heat on the heat pump, all that could be done with smart thermostats. My electric heat is in the form of PTACs (motel units) & those work well if equipped with remote thermostats, the on board ones are always confused due to being right inside the unit. I had never encountered a dual fuel house before I moved here, but saw the wisdom of it the first time we ran out of propane (rookie mistake), and the first time we had a power outage (I still got my shower the addition has its own electric water heater).
Reply to
Eric in North TX

I assume your heat pump doubles as an air conditioning system also.....correct?

The heat pump is only effecient down to about 35 degrees. Also, the heat from a heat pump just isn't like flame heat. You still feel cool. Lack of humidity?

In my area, propane is more expensive than natural gas. I don't know about oil. Propane tanks are safe if not ran into by a big truck. :-)

Hank

Reply to
Hustlin' Hank

PB2 wrote: ...

Although you don't say, this obviously is an air-exchange heat pump; a markedly poor choice for Boston w/ the initial (again apparent) resistance "emergency" heat.

The need for an alternate fuel source is apparent given electric rates in the NE (altho there may be a break for heat pumps; check w/ the utility to see, but I'd not expect it to be enough to solve the problem).

Propane is the alternate fuel source where there isn't an access to natural gas but is also significantly more expensive (and is only going to get more so imo). If the installation is proper, there's no real safety hazard although propane is unlike gas in that it is heavier than air so there are some precautions/code requirements that are different owing to that behavior difference.

I don't know the Renai (sp?)--can't comment. I would presume the efficiency questions, etc., could be answered by looking at their web site/contacting them for information. Are these unvented? I'd not like that, particularly in a really cold climate.

I'd tend to walk on this setup myself, too, unless there are really other things that make it a bargain. Particularly if this heat pump is very old, it's probably on the short list for replacement anyway as well.

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Reply to
dpb

Appreciate the comments. Yes, that's correct - it doubles as an A/C system.

Reply to
PB2

Sorry Hank. That sentence above from you was a totally stupid bullshit statement from one that has no idea what a heat pump can do. Bubba

Funny, mine works quite well and keeps my home warm by itself down to about 15 degrees outside. Humidity is added by a humidifier in almost any type of fuel burning furnace.

Reply to
Bubba

PB2 wrote in news:71782e37-4840-4355-8e9c- snipped-for-privacy@o36g2000yqh.googlegroups.com:

Sounds like the place had had historic HVAC issues and/or cost issues with them since the setup is not typical there. I suspect the owner is/was trying to avoid the expense of "...install an oil based furnace if I wanted.".

It adds to the cost of your purchase indirectly. There is no recoup for changing it unless you are getting a heavy discount. Keep in mind oil was getting up to the $5/gal mark and sure to return there or worse. Propane is probably expensive there and maybe was a bargain whe oil price was up.

I think I'd walk on that one. Avoid the discomfort and expense. Remember, if you sell someday, buyers will have the same concerns as you. Many potentials will avoid considering the home because of the setup.

Reply to
Red Green

To call my reply "stupid bullshit" isn't winning you any friends.

I had a heat pump in my last house 4 years ago. I stand by my statement that it is only efficient down to "about" 35 degrees. Below that, it is cheaper to use other heating methods. I didn't say it wouldn't heat below 35, it just isn't economical. Check the facts.

"Feeling warm" is a matter of opinion. I like to sit around in a t- shirt, so, it wasn't warm to me. I may have felt warm if I'd wear a sweat shirt. Why do people like fireplaces? I'll tell you. Because it makes "them" feel warm.

Hank

Reply to
Hustlin' Hank

Sorry Hank but I still call your reply TOTAL BULLSHIT! What does that have to do with winning friends? Simple test. There are all kinds of papers that came with your heat pump when it was installed (if not, you can find them online.) One of those has the performance data for your heat pump. Check them out. Heat pumps can be very efficient even down to 0 degrees depending on your model. Look at the COP's at the lower temps. IF you dont know what that is then you dont need to be commenting. Bubba

Reply to
Bubba

Let's see what some others have to say about the efficiency of heat pumps as the outside temps drop:

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Hannabery HVAC, Pennsylvania Now with 4 locations Serving Eastern Pennsylvania Homeowners and Businesses for over 30 years!

"In other words, if you set your thermostat for 71 degrees in the winter and your house only seems to get up to 69 degrees. This problem generates many service calls. And sometimes this is caused by a genuine problem but unfortunately, in extremely, cold weather even a properly working heat pump may have trouble maintaining desired temperature. Why is this? When it gets below a certain temperature, in our area around 35 degrees a heat pump loses efficiency and cannot keep up with the heat loss of the structure. "

Which is exactly what Hank stated. BTW, Bubba, Mr. HVAC Pro, where's your website?

Or how about this, from an electric company:

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"2. Auxiliary heat light =93ON=94 (located on thermostat). =95 Supplimentary heaters are providing heat (usually when outside temperature is lower than the balance point, generally 35=B0 or less)."

Oh wait, it gets better. Here they address how with a heat pump, the air coming out of the registers will feel cooler than other heating systems. Which is something else Hank stated, which compelled you to call him names:

"The coils of your heat pump operate at lower heat levels than fossil fuel systems. Air at the supply grills almost always has a temperature ranging from 85=B0 to 106=B0F in the winter. Air at the registers may feel cool compared to that from other heating systems which operate at much higher temperatures for a shorter length of time."

Or how about this from the Dept of Energy:

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"When outdoor temperatures fall below 40=B0F, a less-efficient panel of electric resistance coils, similar to those in your toaster, kicks in to provide indoor heating. This is why air-source heat pumps aren't always very efficient for heating in areas with cold winters. Some units now have gas-fired backup furnaces instead of electric resistance coils, allowing them to operate more efficiently"

"Although air-source heat pumps can be used in nearly all parts of the United States, they do not generally perform well over extended periods of sub-freezing temperatures. In regions with sub-freezing winter temperatures, it may not be cost effective to meet all your heating needs with a standard air-source heat pump."

Now, who should know more about energy and efficiency? The DOE or Bubba?

Reply to
trader4

efficiency and effectiveness are NOT the same thing...

My heat pump is not very EFFECTIVE below 32 becasue it does not keep my house comforatbale but it is still pretty EFFICIENT. Below 32, the BTU that it puts out drops but so does the electric power that it pulls.

Below 32, I switch off the heat pump and use oil.

Mark

Reply to
makolber

snipped-for-privacy@optonline.net wrote: ...

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...

That in particular is a terribly poorly worded paragraph; one would hope DOE would do better. :(

The electric resistance heaters are nearly 100% efficient; certainly higher efficiency than the gas furnace. What they're really talking about is cost effectiveness, not efficiency.

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Reply to
dpb

I would have to disagree that the lower the temperature the less electricity a heat pump will use. The efficiency of a heat pump DOES decline almopst linearly with decreasing temperature. In other words, for every KWH of electricity you put in it, you get more heat out at 45F than you do at 25F. If it were not so, then you could just put in larger capacity heat pumps and cost effectively heat homes where it was regularly 0 degrees, no?

Reply to
trader4

I don't know about cost effective, but I oversize my PTAC units & get heat hopefully at lower temperatures. I upgraded both of my units mainly because the newer ones were higher seer ratings. I also bought bigger units, somewhat oversize for the area, Both the upstairs and downstairs units seem to keep up nicely both hot and cool they dehumidify on AC so I guess I didn't go too far. I have no alternate in that part of the house, the gas furnace is ducted there, and I guess that was the original plan, but the ducts are just too long to be effective, so I blocked them off. There is a natural convection from the original one story to the 2 story, but it isn't enough for comfort

Reply to
Eric in North TX

Once again Trader, you show your incompetence. You obviously dont understand energy and what it costs and what it does. A heat pump is a very efficient machine. It uses electricity but at a much better efficiency than if you were to use just straight electric strip heaters. Sometimes at almost a 4 to 1 ratio. My heat pump warms my house very well at 35 degrees. Piece of cake actually. Certainly the air coming out of the registers is cooler than a gas, or oil furnace. But guess what? It does heat the house to what temp I want it at when its 35 degrees outside and even lower. It also uses less and less electricity, the colder it gets outside but in turn produces less btu's of heat. Then, some magic happens. At a certain point, (it happens to be called the balance point of the home), the heat pump can no longer keep up with the heating needs of the house and the backup heat takes over. Is this all to hard for you trader? I know this is all way over your head trader but please try to follow along. Maybe one day you will actually learn something and I might even let you be like me.

35 degrees?! Wow Trader. You are one dumb sonz-a-biatch. Do I need to point you to one of the performance specs of a heat pump so you can understand what heat a heat pump can produce? Bubba
Reply to
Bubba

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Yeah, Trader probably believes this line too. "Hi Trader. I'm from the government and I'm here to help" bahaha. Trader believes everything he reads. Don't mind him too much. Bubba

Reply to
Bubba

the issue I have is that below 32 the outdoor coils will freeze up and the thing has to go through a defrost cycle, at that point i say forget it and switch to oil..

yes due to the defrost cycle the system is less effeicent. I think the COP at 32 is still probably 2 and above 32 it gets better...

So at 32 it is still cheaper to run then oil and at 45 or so it is much cheaper to run then oil.

I guess if you count the defrost cycle, then yes it gets a lot less efficient below 32.

Mark

Reply to
makolber

No s*** Sherlock. You figure that out all by yourself? The piece you're missing here is that amount of heat that you get for the amount of electricity consumed declines as the temp differential between the inside temp and the outside temp increases. In other words, heat pumps become LESS EFFICIENT the lower the outside temp. Which is exactly the point Hank was making when you called his post stupid BS. It depends on the relative cost of the electric and the alternative fuels, but in many cases below 35, it costs less to use other fuels, like natural gas. Which is why air based heat pumps are not generally used in cold northern climates. Or if they are used, they have a duel fuel system, like nat gas. Maybe you haven't noticed. If you paid attention, the discussion was about Boston. In fact, that is exactly what the OP has. A heat pump system with additional heat from propane.

And once again, I give you links to HVAC companies and the DOE that back up both points of Hank's post, and you just ignore it.

The obvious point Hank was making is that below somewhere around 35, the efficiency of the heat pump has dropped so that you'd spend less money using another fuel, like nat gas.

It's using MORE electricity per BTU of heat that's being generated in the house. That's all that anyone cares about. My gas furnace would use zero fuel too, if it wasn't putting out any heat.

I can understand how it seems like magic to someone like you, who eschews science, engineering and education.

Just glad I never have to let a hack like you anywhere near my house.

Reply to
trader4

ou trader? I know this is

Someone's a little confused here, and it isn't Trader. By the way, thanks Trader for helping me try to edgeumacate Bubba. :-)

How can you make the statement "It also uses less and less electricity, the colder it gets outside but in turn produces less btu's of heat. Then, some magic happens. At a certain point, (it happens to be called the balance point of the home), the heat pump can no longer keep up with the heating needs of the house and the backup heat takes over." ?

The colder it gets the MORE the heat pump runs, not less. How could that use "less" electric? Why do you think the so called "magic" happens? It happens because the manufacturer KNOWS it is more efficient (cheaper) to heat with electric resistive, gas, oil, or anything else. So they have the heat pump kick off at ABOUT 35 degrees. Now, will the heat pump heat below 35 degrees? Yes it will, but not cost effective.

Hank

Reply to
Hustlin' Hank

trader? I know this is

and me thinks it is Hustlin Hank. Read below, Darwin.

Reply to
Bubba

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