Repair or Replace Heat pump?

SirJohnMarch 19, 2012

I have an 11 year-old home with the original Lennox Heat pump model:

12HPB24-8P paired with CB29M-21/26-1P.

From what I can tell, this is a 12 SEER, 2 ton unit. It has a bad expansion valve that will need to be replaced and inspection does show some rusting on the coils but there are no leaks yet. Because of R-22 going sky high, I have been quoted a cost of over $1000 to replace the expansion valve. Is it worth repairing, or given the age and the rusting coils, would I be better served to replace it? I may be looking at having to replace it any way in a couple of years.

To add to this, I've been doing research and it seems this unit is undersized for my house. (A common problem in my neighborhood apparently) It's a 2 story home with a total of 1800 square foot in southern Indiana. From what I have found through research, it seems that my house should actually be using a 3 ton unit, but I have not had anyone come in to give me an estimate on a new unit and I know there are a lot of factors that are considered.

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neohioheatpump

I would replace. If your home is well insulated a 2.5 ton unit might work. If this unit is rusty, and with it being r-22 it seems the only way to go.

I would prefer new unit to be highest eff. single stage around 15 seer and have demand defrost if possible.

    Bookmark   March 20, 2012 at 9:06AM
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ionized_gw

How well has the 2-ton done to keep the house cool and warm while it is operating well?

    Bookmark   March 20, 2012 at 11:15AM
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tigerdunes

SirJohn

If you are confident in the diagnosis, then replace.

there are three equally important components-quality HVAC, the install by dealer, and probably the most overlooked and disregarded is the ductwork system.

these are my minimum specs for a new HP system. both outside and inside units should be replaced to have a properly matched system.

15 SEER, 12.5+ EER, 9 HSPF
best matching VS air handler
full BTUs in both cooling and heating for your rated size
R-410a refrigerant(same as Puron)
scroll compressor preferred
electronic demand defrost preferred
thermostat with "dehumidify on demand" feature
staged backup heat strips
new and correctly sized refrigerant lineset

you want a thorough inspection of your ductwork system. size, overall condition, supply and return lines, insulation qualities, leak test, etc.

any hot/cold spot issues in your home should be addressed.

I would only use authorized dealers for the various brands that provide quotes. see mfg websites.

I would look at Trane/AmStd,Rheem/Rudd,Carrier/Bryant.

Depending on your location, I would not purchase a new HP system that did not have electronic demand defrost.

IMO

    Bookmark   March 20, 2012 at 12:32PM
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SirJohn

Cooling seems to have been fine over the years when it was working. Heating has often been a struggle on this unit. The aux heating coils in it come on constantly in the winter and since I have no additional heating, it seriously struggled in really cold weather and couldn't maintain a temp over 68.

I'm getting a second opinion on the diagnosis so we'll see what they say and then I'll see about getting some quotes on replacement.

    Bookmark   March 20, 2012 at 8:41PM
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tigerdunes

SirJohn

I would say you are undersized.

Request a load calculation in writing.

Your ductwork system should be evaluated as to size, insulation, adequate return(s),leak test. Any hot/cold spots should be looked at and options available to improve.

Based on your location, I would not have a new HP system without electronic demand defrost. Very few brands/models offer this feature.

IMO

    Bookmark   March 21, 2012 at 6:20AM
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mike_home

It is interesting that you say a 2 ton AC does a good job of cooling a 2-story 1800 sg. ft. house, but struggles to keep it warm in the winter.

What are the typical summer high and winter low temperatures? Do you know the size of the heat strips?

    Bookmark   March 21, 2012 at 7:35AM
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brickeyee

"It is interesting that you say a 2 ton AC does a good job of cooling a 2-story 1800 sg. ft. house, but struggles to keep it warm in the winter. "

That depends on lot on local weather.

If the high load fr cooling id only 95F but the low side is down in the single digits it is easy for a heat pump to have problems.

The design issue is that you need very different capacities for heating and cooling loads, but need to selects a single size of unit.

A heat pump that hits back up for a limited time during the coldest days is not that bad.

It can be expensive if you are using only electric resistance heat for the backup though (but even that depends on electric rates).

You can also go to two stage heat pumps and hen match the unit to heating loads.
The first stage may be adequate for most cooling, and can still provides good humidity control.

    Bookmark   March 21, 2012 at 9:07AM
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SirJohn

I got someone else to look at it today. He said he could replace both the coil and the valve for $680 so I may just do that as money is tight right now and hopefully that will get me through another couple of years.

He calculated that I should have a 2.5 ton unit minimum for my house and quoted me for an entry level Tempstar unit, which was surprisingly cheap, but I think I would want something a little higher end if I were to invest in a new system.

    Bookmark   March 21, 2012 at 1:10PM
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neohioheatpump

I think a new system might not be such a bad idea. If he can give you a couple year labor warranty on that tempstar brand. I'm looking at tempstar's equipment and it looks like it is the same as comfortmaker. If he installs it right this could last. They have a 10 year warranty on parts. There is alot of installers out there who are independent and do good work for surprisingly reasonable prices. Smaller brands like tempstar and many others are quality equipment virtually the same as their name brands sold with only a different badge. These smaller name brands sell for a reasonable price. The key is find an installer willing to install them for a good price.

What is he charging to install the newunit?
You could always ask for the 15 seer tempstar unit.

    Bookmark   March 22, 2012 at 7:32AM
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SirJohn

Yeah, this guy is a small independent installer, though he is an authorized dealer/installer for Tempstar. Nice older guy that seemed to know his stuff and you could tell he had been doing this type of work a long time. Quoted me $2700 for a 2.5 ton N4H4 with an FSM4P air handler and 10 kw heatstrip. This is pretty much their bottom end 14 seer unit so I'd have to see how much their higher end 15 seer with ECM air handler would be if I were to go that route.

    Bookmark   March 22, 2012 at 1:06PM
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neohioheatpump

I know you said money is tight but for an extra 2 grand over the repair you have a brand new system. Even their bottom end stuff has a scroll compressor and 10 year parts warranty. It will save you electricity costs during cooling and heating. I would rather have tempstar than goodman personally too. It looks the same as comfortmaker. I would see if the 15 seer upgrade compressor is reasonable. If its only a few hundred more why not? It will save money long term. A 15 seer is roughly 25% more efficient than the old 12 seer.

What part of the country are you in? Whats your climate like? If your spending significant money on auxiliary heat the 2.5 ton new system should pay for itself in a reasonable amount of time.

    Bookmark   March 22, 2012 at 3:15PM
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tigerdunes

" A 15 seer is roughly 25% more efficient than the old 12 seer."

The statement above is simply not accurate, maybe up to 15% savings on AC side only. HSPF would determine heating efficiency savings.

While not a particular fan of low end systems including Tempstar, I agree that your money would be better spent on the Tempstar over the repair.

IMO

    Bookmark   March 22, 2012 at 3:49PM
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SirJohn

I called and asked about the 15 seer Tempstar. The upgraded unit would be the N4X5 with a FXM4X air handler. This combo is 15.25 SEER and 8.7 HPSF. It also provides an ECM motor and qualifies for my power utilities $200 rebate so total cost would be $2900. Seems like a no brainer if I go with the replacement.

    Bookmark   March 23, 2012 at 5:26PM
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tigerdunes

I agree. Just don't expect 25% savings on AC side.

Verify warranty.

IMO

    Bookmark   March 23, 2012 at 6:11PM
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tigerdunes

For SirJohn

Just to verify, what size are you looking at?

Has dealer even bothered to inspect your ductwork system both supply and return to make certain larger size condenser can handle?

I hope you are looking at 3 ton rather than 2 1/2 ton. You can not increase size without knowing ductwork system can handle extra CFMs both supply and return.

You will be making a mistake if this is not thoroughly reviewed carefully with dealer. Just so you know.

What thermostat will be provided?

A lot more to this than just going up in size.

IMO

    Bookmark   March 23, 2012 at 6:35PM
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destructo

It's important to remember when installing an air source heat pump into an existing home that the sizing can be limited by the size of the ductwork and the power supply. A newer 2.5 heat pump would probably draw about the same amount of power as the older 2 ton, but if you go higher you'll want to look at how much of your power supply it will take.

But the thing that usually determines heat pump sizing in older homes is the ductwork. You'll probably want to install the largest unit that your ductwork can support. Air source heat pumps move a lot of air and if your ductwork is too small for the unit it will result in maintenance issues/ shorter unit life.

Here is a link that might be useful: Heat Pump FAQ

    Bookmark   March 23, 2012 at 9:11PM
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mike_home

"But the thing that usually determines heat pump sizing in older homes is the ductwork. You'll probably want to install the largest unit that your ductwork can support."

I am not sure if I agree with this statement. I thought the first rule is to size the heat pump for the cooling load. If the duct work is too small for the required heat pump size, then it needs to be addressed. If it turns out the duct work is larger than required, then I see no harm in this. It is not a reason to install a bigger unit.

    Bookmark   March 24, 2012 at 1:41PM
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SirJohn

Well I wasn't there the whole time that the guy was there so I'm not sure what all he looked at to do the calculation and my wife couldn't tell me. The Tempstar would be a 2.5 ton (the old was 2.0 ton). I did find my old home energy audit that my power company did for free 9 years ago. And I found a couple of very good estimators (I know this isn't as good as a manual J). Based on all the info I have, it seems that 2.5 would be the correct size. One of the things in my favor is that I really don't have a lot of glass for a house of my size (double paned vinyl framed) and my house is built to post 2000 standards for insulation. Check out the estimators below. Very interesting and much more detailed than the usual rough calculators.
www.bpa.gov/energy/n/projects/PTCS/HeatPump_SizingCalculator.xls
http://pse.com/savingsandenergycenter/ForHomes/Documents/HeatPumpSizingCalculator.xls

    Bookmark   March 24, 2012 at 7:15PM
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SirJohn

Just a follow-up that I decided to go with the 2.5 ton Tempstar NXH5/FXM4X system. The installer said that this is fine for my duct system. If we went larger, it may be a problem. By the way in case anyone is wondering, this exact system is sold using the exact same model numbers by all the old ICP brands (Heil, Comfortmaker, ArcoAire, etc), they just stick their own brand label on it. Since I was curious about how all these companies compare under the Carrier umbrella, I decided to hunt down technical documents for various models and found that this heat pump combo is actually the exact same as the Bryant 215B/FX4DN and the Carrier 25HBC5/FX4DN combos. The specs are all identical as are the AHRI test results (this combo is listed as HSVTC for all the brands). Similarly, the bottom of the line ICP brands N4H3 is the same as the Bryant 213B and the Carrier 25HBC3. So at least for the entry level models, there is no difference between any of the brands in the Carrier Group. It will just come down to which installer seems to be best if you are looking at the lower models for these brands.

    Bookmark   March 26, 2012 at 2:49PM
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neohioheatpump

thanks for that followup with that information. Its good for people to know that you can get a good system for a reasonable price. Many of the 'low-cost' brands are decent equipment and will provide years of service with a good install. Let us know how this new system works for you and if its saving you much money in energy.

    Bookmark   March 26, 2012 at 2:55PM
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tigerdunes

For SirJohn

New lineset to be provided?

What size heat strip?

IMO

    Bookmark   March 26, 2012 at 3:06PM
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