furnace decisions part 2

rich0372March 2, 2013

Ok so I've made up my mind to replace my exsisting oil hot air furnace with a gas one hopefully NG but maybe propane anyway on with my questions.
I've had four HVAC contractors come to my house to give me quotes and they all look at things different. Only one did a true load test another did a quick one by measuring rooms but didn't measure windows or ask about insulation. the other two only measured the duckwork actually one didn't even do that. Two of them said I should add another return for more airflow, with no mention of a return with the other two, it really is frustrating to say the least.
So as for as sizing the HVAC guy that did the load test said I needed a 60k btu furnace The one that did a quick one said I needed a 70k and the other two said 80k.(My house is 1000sf with 550sf finished basement I'm also having my insulation upgraded to R49 attic R15 walls and R21 sill plate spray foam). Does 80k seem a little high?? one of the HVAC guys said 80k was good cause if I get a two stage it would run in the first stage most of the time and if I got a 60k it would always be in second stage. As far as AC all said 2.5 ton except for the guy that recommended the 60k furnace.

Btw I'm looking for a 95 percent eff furnace or higher, I've looked at trane, AS, Carrier and lennox all either two stage or modulating. I'm also getting an AC 15 seer or higher.
Is a two stage AC unit really worth it with the size of my house? I figure Im only really cooling the upstairs as the bsement is always cool anyway.
One other thing is a modulating furnace worth the 800 to a thousand bucks more for them over a two stage.

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What was the result of the load calculation? I would think even a 60K BTU furnace is oversized for a 1000sf house. This furnace will probably spend most of its time in the first stage. You can see the guy who did the load calculation is trying to size the furnace properly. The problem is there are very few models available in a size smaller the 60K BTU.

You don't need to spend extra money on a modulating furnace. Two stages are fine. The 2-stage AC is nice, but you would have to move up to a 3 ton unit. Typically the first stage is 70% of the total so you will have about 2.1 tons of capacity. In your situation it is not going to make much of a difference in comfort. The 2.5 ton single stage unit is nice to have, but not necessary.

    Bookmark   March 2, 2013 at 5:56PM
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I do not know what the load calculation was it was not told to me, just what he recommended. Are you saying I should get a single stage 2.5 ton instead of the 2 ton the load cal called for. The HVAC guy is trying to sell me on the trane xli16 in 2 ton saying it will be able to dehumindify my house better.
Should I just keep getting quotes done and only keep the guys that do a load cal?? Are guys just thinking because my house is small they will just eye ball it why wouldn't everyone do it right? By the way I'm in Ct so it's cold in the winter and hot and humid in the summer.

This post was edited by rich0372 on Sat, Mar 2, 13 at 18:27

    Bookmark   March 2, 2013 at 6:25PM
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It seems to me that the Trane XV95 paired with an XL15i would be the absolute top of the line in Trane. Since the 95 is 2 stage that would be, A 60K model, I think, would be a true 37,800 for the 1st stage and 58,200 for the second stage.

I also like the XL15i over the XR15 in the shielded top. Both have average noise ratings. A good feature is that the Trane HP line has electronic defrost on demand. I think the 16 would be overkill. What causes the humidity problem is oversizing the HP, so watch out for that. Most of the high-end thermostats have a feature that will reduce humidity without a separate De-humdifier by spinning the fan only.

Regardless of the brand and features, the most important thing is the load calculation and installation. You must trust the contractor in making the correct decision. To do that, he or she should share all information with you and explain in detail the reason for the proposed equipment.

If they don't, move on to another contractor/company that is more transparent and get at least 3 proposals.

BTW, I have the XV95 and XL15i

This post was edited by audiomixer on Sat, Mar 2, 13 at 18:53

    Bookmark   March 2, 2013 at 6:49PM
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Just fyi I wasn't planning on getting a HP just an A/C unit...I didn't think it was cost effective as I have pretty high electric rates but I guess it would be if I wind up with propane and not NG

    Bookmark   March 2, 2013 at 7:12PM
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Others here can speak better for what's more cost effective for you in your area.

For me, it's the best of two worlds: Dual Fuel and AC. My weather is mild and I can set things up to be primarily HP or primarily NG.

Of course, right now NG rates are lower and more cost effective than electricity, but that may change. Who knows ?

The way I look (now) at these systems are that is like buying a car. I'll use it and don't really expect to recover my installation costs. After all, (and many will disagree) I figure that the average life of an HVAC system is around 10-15 years.

One final thought. I would recommend an extended labor warranty with any system. So, figure that into your cost.

This post was edited by audiomixer on Sat, Mar 2, 13 at 20:34

    Bookmark   March 2, 2013 at 8:28PM
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You did not state in your first post that the load calculation called for a 2 ton AC. You should follow the calculation and not over size the unit. The 2-stage unit will do a better job dehumdification, but I am not sure how much better given it is the small size.

Most contractors don't want to spend the time to do a proper load calculation. They will use a rule of thumb which tends to over size the equipment.

You have four quotes. Why not go with the contractor who did the load calculation?

    Bookmark   March 3, 2013 at 12:03AM
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Mike I only got three quotes so far the other guy didn't get back to me yet on price. I did like the company that did the load test but they are about $2000 more for the same equipment so I'm torn cause $2000 is a lot of money, to me anyway

    Bookmark   March 3, 2013 at 1:31PM
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I agree paying an extra $2000 for the same equipment does not make sense. If you like the other contractors, then tell them you feel the sizes are too big. Have them explain how they came up with the sizes.

Perhaps the fourth quote will have the right size at a fair price.

    Bookmark   March 3, 2013 at 6:53PM
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Mike I did ask one of them, he said he wanted to up size me a little just in case i would expand my house I would be able to tap into it with no problem. He said it was 75 bucks more for the 80k btu vs the 60k and with it being two stage it wouldn't short cycle and would probably run in first stage most of the time. This contractor didn't measure my house at all but did measure my duckwork and was the only other guy to say I needed more return air. The funny thing is he did quote me on a 2 ton A/C like the guy that did the load test.

    Bookmark   March 4, 2013 at 6:27AM
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Stepping up one size for the furnace is relatively inexpensive. This is why many contractors will suggest this. The larger size is more forgiving for a 2-stage. But why spend the extra money on a 2-stage furnace that runs as a single stage most of the time?

Tell the contractor you are upgrading the insulation and would like the 60K BTU furnace.

    Bookmark   March 4, 2013 at 6:46AM
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