I purchased a plain jane McQuay 3 ton geothermal heat pump. They shipped one with a few extra features, including a desuperheater. The salespeople told me that it's easy to disable, but I don't want to damage it in any way.

Will disconnecting the desuperheater pump cause any damage to the refrigerant system?

Thanks!

no damage at all.

Agreed - no impact on refrigerant system from deactivating the DSH

In fact, do NOT power / activate the DSH pump until it is plumbed and bled free of air.

If it is already plumbed and bled (full of water) turning it off needs to be done with more care.
j

Thanks, that's what I was hoping for ... information I can use from people who know what they're talking about. Nothing is plumbed since I was not expecting this option. I can't afford to hook it up at this time, but it should make a decent project next summer.

As a DIYer, I just wish I'd discovered this site *before* I made any purchasing decisions.

Return the favor by letting everyone know how it goes.

Posted By jonr on 16 Jul 2011 11:00 AM
Return the favor by letting everyone know how it goes.

Will do, but it's going to take a while. It took me a month just to wrestle it into the house. At present, I've got a few more hours work getting it attached to the existing duct work.

It's an open loop system with slightly acidic well water (6.3 pH). I'm still awaiting a filter and a pH adjuster to keep the particulates out and try to bring the pH up to 8 before I plumb the thing up and put it through initial testing.

Oh, and I still need a thermostat. I'm thinking that I may just go with heating only. My reasoning is that running a swamp cooler during the hottest parts of the summer would be cheaper than running the heat pump and will put less hours on the coil, saving it for the more important heating season.

What city are you in / near?

I'm curious, why do you want a pH of 8 vs 6.3?

Posted By engineer on 17 Jul 2011 09:11 AM
What city are you in / near?

Middle of nowhere Montana, Missoula is the nearest major town.

Posted By jonr on 17 Jul 2011 11:03 AM
I'm curious, why do you want a pH of 8 vs 6.3?

The installation instructions call for a pH of 7.5-8.5. These instructions are ambiguous however since they go on to state that once the pH is adjusted that you can now add antifreeze ... assuming a closed loop. I decided to adjust the pH in hopes of extending the life of the copper coil.

What is a swamp cooler?

A device to cool the air. Works best in arid regions. Cooling results from evaporation.

A swamp cooler is an alternate method of cooling a home by humidifying the air to the point where it feels like living in a swamp.

Just kidding...

Swamp coolers work by taking in warm dry outside air and humidifying it by passing it over a wet pad or mesh. That causes the dry bulb temperature of that air to fall. Technically they swap sensible for latent heat. They work well in hot dry climates, and cost little to operate since they only require a blower and a small pump. They do consume quite a bit of fresh water, 100 gallons or more per day.

Missoula is probably a good area for swamp coolers - a quick check of weather info suggests dewpoints in the 40s are commonplace - very dry.

There are corrosion inhibitors designed for open loop systems although I don't know what the cost works out to. I would target a pH of 7.5 since the higher it is the more problems you get with hardness deposits.

Thanks for the info on the swamp cooler! I have never heard of it before.

Swamp coolers are cheap to own and operate. As for consuming 100 gallons of water a day, that sounds like an overestimation to me, but of course it depends on your circumstances. Around here, there are only about 30 days a year when the house gets unbearable, and it's only unbearable for 5 or 6 hours on those days.

A swamp cooler (or more accurately, an evaporative cooler) is kind of like a poor mans heat pump. It takes heat out of the air by evaporating water. The downside is that it then pushes that air *AND* the evaporated water through your house. Because of that, you'll notice that cold surfaces will "sweat" and open potato chips will lose their crunch. But for my purposes, it works great, chilling the house very quickly and cheaply. Only on the hottest days do I have to run it constantly, and when I do, I doubt that it consumes 5 gallons of water (though that's just a guess based on having filled it by hand when it was new and I didn't have the right fittings to attach it to the water system).

As for the heat pump install, I expect to receive my filtration/pH system this weekend, so I'll probably be test ready next week sometime .... I hope.

Posted By jonr on 18 Jul 2011 10:13 AM
There are corrosion inhibitors designed for open loop systems although I don't know what the cost works out to. I would target a pH of 7.5 since the higher it is the more problems you get with hardness deposits.

The way I understand it, the pH adjusting ability of this custom filter (it just uses a standard water filter casing) will deteriorate over time, so if it achieves 8.0 pH initially, when it's shot, the pH will be back to 6.3. I intend to monitor the pH constantly so that I replace it before the pH hits 7. I won't know until I've put it through one cycle just how the pH will deteriorate over time, but just guess that it will be linear, the average pH will be 7.5. Just have to see how it all works out.

BAD NEWS

Finally got my water conditioned, plumbing plumbed and flushed. Pressured up the heat pump for the first time.

It has an internal leak. Water all over the bottom of the housing. I imagine this happens, but it's really bad news for a DIYer because this get's into the realm of things I'm not qualified to deal with.

I'm guessing I won't be able to talk to the vendor til Monday.

Does anybody have advice ?

Thanks

If there is a leak and you have plumbed everything correctly it is a warranty issue. That doesn't mean they will cover more than parts....
Good luck,
j