Questions on new gas furnace and AC

[trader4]

Going through the quote process for my new furnace and AC and came up with two questions:

1 - Are new refrigerant lines required or recommended? The existing system is 26 years old, still working no burned out compressor, etc. One company says they have to be replaced, other I didn't talk with on that specific subject, but their quote calls out flushing and re- using the existing ones.

2 - The new furnace will be direct vent, so it leaves the gas water heater orphaned on the existing chimney that was shared with the gas furnace. Is a chimney liner required or recommended? Chimney is clay flue lined, most of chimney is entirely within the house, except the last 5 ft or so which is in a wood siding chase above the roof line. Don't have the exact measurements of the flue without going on the roof, but guessing it's about 9 X 6 or so. Again, one company says must do, the other says not needed.

[Molly Brown]

1. Why are you replacing your HVAC? Is the new A/C going to be bigger? If it is then the refrigerant lines probably need to be of larger diameter as well and if not you don=92t need to replace them.
2. Does your fireplace share the same chimney?

[trader4]

It's 26 years old and with the $1500 tax credits and rebates, it's cost effective to replace it.

Is the new A/C going to be bigger?

No, both 5 tons

No. The chimney has one flue for the existing furnace/water heater and one flue for the fireplace.

[jamesgangnc]

There is not a downside to lining the side of the chimney that the hot water heater will be using except cost. I suspect you're probably getting some condensation in there already when the hw heater runs without the fireplace in the winter. Is this a one or two story house? Is the chimney brick? What's the total height of the chimney? How exposed to the elements is it?

Another option would be to go with a condensing hw heater as well. Then nothing is using the chimney any more.

[ransley]

I spent 1000 this year fixing AC piping leaks on a 16 yr old system, a

26yr old line could easily become overstressed fitting new equipment, nobody will guarntee that line.

[trader4]

2 stories. Chimney is block with clay flue. From the basement up, most of it is entirely inside the house, surrounded by interior walls all the way, except for the last 5 feet or so that is in a cedar siding wood chase.

Yes, I'm considering that too, but not the most likely option. And certainly not from the quote the one guy gave me, $1800.

[Steve Barker]

I can answer only #2, because i've ran into this exact situation 3 times now. The answer is to have a liner installed. The clay flue will never run hot enough to stay dry, and much caustic condensation will run back down it. My HVAC man recommends a 4" liner, properly capped on top, hooked to b-vent pipe to within a couple feet of the water heater. This minimizes condensation as much as possible.

[hrhofmann]

Pardon my ignorance, but what is a b-vent?

[The Henchman]

Going through the quote process for my new furnace and AC and came up with two questions:

1 - Are new refrigerant lines required or recommended? The existing system is 26 years old, still working no burned out compressor, etc. One company says they have to be replaced, other I didn't talk with on that specific subject, but their quote calls out flushing and re- using the existing ones.

---------------

New refrigerant lines are wider now, like 1 1/8" and help greatly with efficiency. I'm surprised the people that gave you quotes did not tell you this. What is the length of the line??

New A/C units need larger diameter lines to reach their stated efficiencies. The shorter your line, the more efficient it becomes too. The further from the house or your blower/A coil the higher diameter line you would need. That new line they want to give you might allow that new a/c they want to install to run at stated capacity. Keeping the old lines might reduce that capacity making your new unit run harder.

It'd be great too to get new insulation for those lines.

[ransley]

You can bypass the chimney without a condensing unit if you powervent the exhaust, I did that with my tankless. My new furnace is condensing, In removing the furnace from the chimney the chimney got to cold and downdrafted. I just didnt want to risk trying to make a chimney reverse draft every time the water heater went on. Weigh the cost of a liner vs 200 for a power vent and stainless vent hood, im not including labor, and a completely new water heater and or a liner. Or why not leave it for a year it wont hurt anything.

Copper oxidises before it develops the green patina, it wears away. I can also imagine its thinner from fluid pumped through it for 26 years. Its aged and stiff. To put a new bend in it I bet will stress it and could crack it if the bend is big enough. Is it worth breaking and losing your charge. It will cost twice as much to replace and refill your system if it goes and it wont be under warranty.

Be sure you get in writing that they come back next summer to test it, to be sure thyey installed it right, that it works.

[Steve Barker]

The regular ol' double wall vent pipe.

[hrhofmann]

OK - But how does that translate to b-vent??

[Steve Barker]

That's what the shit is called! What part don't you understand?

[trader4]

glegroups.com...

I have written quotes now from 2 contractors, price only from #3, waiting for #4. I brought up the lines with the first contractor, Carrier guy, and he said they needed to be replaced and were in his quote. From then on, I didn't even think to ask, because I guess I figured they all would replace them. None of the other guys said anything one way or the other. But the other written quote calls out flushing the existing lines.

I talked with the Carrier guy about this on the phone and he's saying the same thing you said above. That they should be 1 1/8" From talking to him and googling, it appears however that it's acceptable to reuse the existing ones if it's difficult to replace the existing ones, eg, they are covered by drywall, run inside walls, etc. Mine are easily accessible in the basement.

22 ft. I think the new ones could be routed on a shorter path, to bring it down to 15 or 16ft, if they wanted to do it that way.

My current thinking is to get both the new lines and chimney liner.

Regarding the chimney liner, from what I can gather from googling, it appears the answer is, it depends. I found some guidelines that say if the chimney is entirely inside, then it doesn't need to be lined. That is what one of the contractors told me too. Then, if it's not, there are some rules of thumb regarding flue size. If its a 3" vent, then it doesn't need a liner if the flue is 49 in sq or less. With a

4" vent, if it's 88 in sq or less it's OK. Haven't gone up to measure mine yet. But one thing is clear, regardless of the guidelines the only downside to the liner is the upfront cost and it's the option that is the most sure.

[Ralph Mowery]

messagenews: [e-mail]...

Several years ago I had a heat pump system replaced as the old one was about

20 years old and was giving problems. I had everything but the duct work and the power witing going from the main breaker box to the disconnects replaced. That way if anything goes wrong the installers can not point their fingers at anyone but theirselves. A few feet of line probably does not cost all that much anyway. As someone pointed out, the lines may need to be differant sizes. Especially when going from the old r-22 to the newer refrigerant.

[trader4]

ps.com...

Thanks for all the input on both issues. I'm going to get the new lines and a chimney liner. I came up with another idea. Since the water heater is about half way through its life, I'm thinking of using an aluminum liner which is a lot cheaper than stainless steel. It won't last as long, but should last as long as the water heater. At that time who knows what products will be available, tax credits, rebates, etc. So it might bet converted to direct vent, or tankless, etc and then no need for the liner anymore.

[Evan]

Yeah, this sort of thing happens, OFTEN, because many homeowners have never heard of something called a RFP (Request for Proposals) or Bid Specifications Packet...

If you call in 4 companies to look over your project and aren't very specific AND very identical in what you tell them during your walk around with each companies representatives, you are in actuality getting 4 different quotes on 4 different projects which will include differing options at the discretion of the companies involved and will most definitely have vastly different scope of work factored in... In your example, which ones say in the bids that the lines will definitely be replaced versus the ones that say nothing about them ?

The more detailed the description of work you give the bidders, the more accurate your bids will be and the contractors will know what needs to be replaced to accomplish your work... Everyone will be on the same page... Differences in bids often result from poorly defined scope of work and not specifying what equipment you desire to have installed (different companies can get different brands cheaper than others) and therefore what you end up with is having to choose between bids in a large range from high to low without having a very detailed breakdown of what you will be getting for your money...

~~ Evan

[trader4]

Yes, I agree. And I'm fairly well educated on the HVAC basics. I can only imagine what happens with a total novice homeowner. Another example is permits. Half the companies just include them. The other half say because the costs vary from location to location, they will pull them, but I then pay for whatever they cost at the end of the job. Either way is OK with me, but I wonder how many people forget to factor in that they have an extra $300 coming with some of the quotes at the end that isn't reflected in the price they are looking at. I bet after a week or two half of them forget about it and consequently, one guy's quote looks $300 better than another.

In the case of the refrigerant lines, I did think to ask the first guy and since he said they always replace them, my mind shifted to that being it's a whole new system, different refrigerant, etc, everybody would just replace them. Fortunately, I figured it out in time and at least it was clear on the quote from the company that wanted to re-use the existing lines. They didn't hide it. Clearly what one has to do is learn along the way and then go back to the contractors of interest to find out any adders necessary to make the quotes comparable.