matching 10 and 13 seer

[wrknlate]

I'd like to know if there are any problems with installing a 13 seer heat pump condensing unit wit a 9 seer air handler. Other than not achieving full 13 seer. The air handler is a 20 year old comfortmaker with a piston metering device.

[chucko615]

20 years old. Don't you think it's time to buy a new air handler. You can only squeeze a nickel so hard.

[Downeasthvac]

You should absolutley not install that condenser without replacing the air handler. Your contractor should tell you that. Why spend the money if you arent going to do it right?

[RyanHughes]

That sounds like pressure problems waiting to happen, let alone performance loss and possibly voided warranties. Do it right the first time - trust me.

[yorkdude]

Acctually, I have done it before without any problems worked great! But some systems dont like it. Youll know for sure if its going to work as soon as you kick it in to heating mode.. Just do it once! Do it the right way. Might as well upgrade the whole system.

[Kevin O'Neill]

Bristol (they make compressors) just had an article published in RSES Journal. They matched a 3 ton, 13 SEER outdoor unit to a 3 ton, 13 SEER indoor unit. Then they tested it. Surprise! They got 3 tons & 13 SEER. Then they matched the same outdoor unit to a 3 ton 10 SEER indoor unit. They got just under 2 tons and 8 SEER. If your unit is way over sized for your house, go ahead. It may still do the job. But I hope your electric rates are very low. Or you could do it right and save money in the long run.

[RoBoTeq]

Acctually, I have done it before without any problems worked great! But some systems dont like it. Youll know for sure if its going to work as soon as you kick it in to heating mode.. Just do it once! Do it the right way. Might as well upgrade the whole system.

NO, it didn't work great at all. Maybe it worked and you lucked out, but there is no way that a mismatched system on a heat pump can work great when the indoor coil is not of a suitable size comparable to the heat pump coil.

Absolutely do not mismatch heat pump components.

[AtticAce]

airhandler. I have done this many times, the system will work ok, if it was oversized originally. I find in my area many older installs were oversized. Actually in my area just about every install I see is oversized.

I know I will catch hell on this site from a few folks, but sometimes the airhandler cannot be economically replaced. In the future these folks will have no choice, they will have no options. When that day comes they will have to spend the big bucks.

I just did one of these very installs in a condo in Philly the unit is in a closet which is reached by climbing through a door a foot above the toilet tank. To replace the 4 ton air handler the ceramic tile tub enclosure will have to be removed, as the plumbing stack runs just next to the service door above the toilet.

In the same building another blower is reached by removing a tiled door in the tub enclosure.

The unit runs with normal pressures, I have no idea what the seer is and they do not care. I installed an expansion check valve on this unit. The condo should have a 2 ton heat pump.

[BaldLoonie]

Chances are the refrigerant level will have to be changed twice a year. TXV won't help, it's coil size that is the killer. The small indoor coil functioning as a condenser in the winter will need charge reduced for heating, then put back in for cooling. You can get by with mismatching for cooling only with large SEER loss and capacity loss and a TXV does help. But nothing can compensate for the small indoor coil.

[yorkdude]

Yes, It did work Robo Man...Same Tonage,diffrent seer rating. We do work for a property mangement company at some apartment complex where its nearly impossable to replace the fan coils. My boss has me replace the condenser only (13 seer) . Do i think its the right way of doing things? No. I dont make the rules, i just do as im told. But it does work, we havent had any call backs. Pressures/temps are all text book.

[docholiday]

Bristol (they make compressors) just had an article published in RSES Journal. They matched a 3 ton, 13 SEER outdoor unit to a 3 ton, 13 SEER indoor unit. Then they tested it. Surprise! They got 3 tons & 13 SEER. Then they matched the same outdoor unit to a 3 ton 10 SEER indoor unit. They got just under 2 tons and 8 SEER.


That was straight air, the HP didnt work.

[DavidInAustin]

With the exception of "Have to do jobs" - The efficiency will be shot - example, if it was a 4 ton unit - it may only be as efficient with roughly a 2.5 ton capacity. Even changing the TXV will only marginally help it. There is a wonderful article on this subject exactly, however I will have to search for it. In a nutshell - It doesnt work.

I believe the article below mentioned was it - published in RSES Journal

[docholiday]

The problem is nobody cares about effiency, that is not the problem. A heat pump is a system, not an outdoor unit (unless packaged of course). The coils must match by design in order to work properly in both heating and cooling. Yes efficiency can suffer but more importantly working period is another story. For those that "do work", there is then the issue of performance, capacity and reliability.

Too much superheat in one mode or another... dead compressor (over time), poor defrost, poor capacity, poor latent performance etc. Too little in the other direction and dead compressor, poor defrost, noise etc. Capacity can be huge, for instance, if you now lack 3-6,000 btuhs in heating mode, you now have to make that up with electric heat when that 6,000 should be mechanical, or inability to keep the house comfortable when it's 95 degrees outside. Long, loaded run times = higher operating costs. The list goes on to include possible oil return issues.

A mismatched HP will not be supported by any mfg or distributor. That leaves the contractor who will ultimately blame the equipment when the HO complains of high repair bills or more than usual service. Regardless, the consumer gets screwed.

[RoBoTeq]

Yes, It did work Robo Man...Same Tonage,diffrent seer rating. We do work for a property mangement company at some apartment complex where its nearly impossable to replace the fan coils. My boss has me replace the condenser only (13 seer) . Do i think its the right way of doing things? No. I dont make the rules, i just do as im told. But it does work, we havent had any call backs. Pressures/temps are all text book.

I didn't argue that it didn't work, I argued your stating that it worked great. Again; it may have worked but it did not work great. Please read my posts a bit more carefully if you are going to get upset over them.

[DavidInAustin]

Doc H - I agree with you totally - However if you read my post - I am using the word effiency in conjunction and as a word that describes capacity. Simply put, the capacity is severily effected in any case. This as stated in the journal as noted below. We are in fact saying the same thing. Somehow one can get confused with (working or not working) as opposed to effiency. They are the same. Effiency is a much better term for how well something works with the minimum amount of input. At one end of the spectrum of effiency - If a contactor has failed - It is no longer efficient

Just a simple point. Thanks anyhow...

[BigJon3475]

With the exception of "Have to do jobs" - The efficiency will be shot - example, if it was a 4 ton unit - it may only be as efficient with roughly a 2.5 ton capacity. Even changing the TXV will only marginally help it. There is a wonderful article on this subject exactly, however I will have to search for it. In a nutshell - It doesnt work.

I believe the article below mentioned was it - published in RSES Journal

10 + 13 = 8

[AtticAce]

Chances are the refrigerant level will have to be changed twice a year. TXV won't help, it's coil size that is the killer. The small indoor coil functioning as a condenser in the winter will need charge reduced for heating, then put back in for cooling. You can get by with mismatching for cooling only with large SEER loss and capacity loss and a TXV does help. But nothing can compensate for the small indoor coil.

I have done this many times the system works fine, never have I had to add or subtract refrigerant.