heat pump

[tom in maine]

The separate heat pump offers much greater serviceability than the one piece units.

Stratification is just not that different between the two units.
Given the longer recovery times of any HPWH, you pretty much want the whole tank hot all the time.

The lower cost of the all in one units is compelling. A $300 unit separate unit that is one generation back is even more compelling.

I hope they all last a long time. Between the two, I would prefer to have something that I can work with that is less expensive.

 

[woodgeek]

The separate heat pump offers much greater serviceability than the one piece units.

Stratification is just not that different between the two units.
Given the longer recovery times of any HPWH, you pretty much want the whole tank hot all the time.

The lower cost of the all in one units is compelling. A $300 unit separate unit that is one generation back is even more compelling.

I hope they all last a long time. Between the two, I would prefer to have something that I can work with that is less expensive.

People can get whatever they want/like, of course. 2 mins of googling showed me the 50 gal Geospring lists for ~$1000, and I am eligible for a $300 fed tax credit and a $400 rebate from my local utility. Seems like I could get the latest, most popular and eff model for $300 when the dust settled. If I didn't already have a HPWH.

 

[woodgeek]

An personally, given the ongoing phaseout of R-22, I think 'serviceability' has to be problematic. In 7 years, no more can be produced. What will recycled cost then? The all in one HPWHs are using R-134a, and if there are millions of geosprings installed, don't you think someone will be able to service them?

 

[pybyr]

Would you buy a two piece refrigerator for the same reasoning? A GE HPWH costs less than most fridges at this point, a lot less with rebates. As for reliability, get/check the warranty on the HPWH. Have never heard good things about the tankless propane units re reliability or hot water 'quality'.

Actually, I, myself, would buy a two-piece refrigerator, gladly, if I could buy a well insulated/ well-made "box"/ body that would have an indefinite and very long life, and a separate compressor assembly that was servicable or could be replaced without having to change the still-good structure of the unit. I'd be even more "into it" if the refrigeration assembly offered the option to dissipate the heat into water instead of ambient air, so that the "waste heat" could be used for something (or run as a "ground source" arrangement with my constantly-running gravity-fed spring). But I probably don't qualify as having generally-representative consumer buying preferences...

 

[tom in maine]

I think those were called Monitor Refrigerators and they were made by GE back in the 20's.
Dick Hill's father worked on the design.
Small world.

 

[BoilerMan]

An personally, given the ongoing phaseout of R-22, I think 'serviceability' has to be problematic. In 7 years, no more can be produced. What will recycled cost then? The all in one HPWHs are using R-134a, and if there are millions of geosprings installed, don't you think someone will be able to service them?

As a refridgeration tradsman, I can tell you R-22 is not going anywhere any time soom and the 1 or 2 pounds that could be needed to srevice a HPWH or any small appliance will be available. Or is could be retrofitted with R134a, or even R410, the sky is the limit (no pun intended). A simple compressor change and flush the system and you can use about any refiidgerant that you want in a small copper piped appliance.

TS

 

[woodgeek]

Got it, but what is the rated eff after the swap?

 

[tom in maine]

My understanding is the efficiency is higher with some of the replacements.
The issue with all in one units is going to be the lack of ability to replace the tank when the time comes there is a leak.
Hopefully the tanks will last a while.

 

[BoilerMan]

My understanding is the efficiency is higher with some of the replacements.
The issue with all in one units is going to be the lack of ability to replace the tank when the time comes there is a leak.
Hopefully the tanks will last a while.

The refrigerant does not as much effect overall system efficiency as the compressor type and heat transfer surfaces do. It is a misnomer that the refrigerant is the efficient part, most commercially available refrigerants are very similar in efficiency in the systems that are designed for them to be run in. CFC's (R-12, R-22 etc.) are still the best at all things heat moving, but worst for the ozone layer. HFC's (R-134) are not ozone depleting, but runs at higher pressure differential which makes it slightly less efficient in retrofits, in most cases. Oils that are used with different refrigerants will not get along with certain types of compressors. Propane is actually an excellent refrigerant as well as environmentally friendly and widely used in Europe, but flammable substances in any system is forbidden in North America, for obvious reasons.

Anyway, yes if the tank goes then the unit is basically a throw-away. If the compressor goes, well you get the idea.

The overall efficiency of a combined unit or a separate unit will be very close in any case, line losses between the tow in the only real difference. Also a separate unit has a circulator to move water to and from the HP, but is much easier (read actually possible) to clean scale out of than and all-in-one unit. It's a toss up, but separate it is for me, as I already have a HUGE SS indirect.

TS

 

[woodgeek]

Doesn't really jibe with my understanding. The quoted EFs for the separate and all in one units differ by a significant amount (e.g. 1.8 versus 2.3), might be the result of bad model or other crp, but that's what I have read.

We also agree that pretty much any material with a certain boiling point at a given pressure can be used a refrigerant, including propane. But I disagree that substituting the refrigerant in an existing unit doesn't ever (or in general) reduce the efficiency. If there were a non-combustible substitute for R-22 that had the same eff as a drop in retrofit, seems that we all would have heard about it and starting using it years ago. There are reports of (hack) HVAC guys subb'ing propane into R-22 systems (and pocketing the $$ charge for recycled R-22). Propane eats the lube, compressor dies a few months/years later, and no one is the wiser.

 

[BoilerMan]

I said the systems they were designed for, retro is another story. I was getting as when people say R12 systems are better than R134a, it's the system not the refrigerant. Retros are another story, you oils substitute oils, all carrying heat around the system and reducing the overall watt-to-work numbers. Oh yes the propane hacks, thankfully I'm in a pretty much non-A/C area, so the vast majority of our work in commercial.

TS

 

[woodgeek]

So if millions of geosprings are installed in 5 more years, and compressors start to go, why can't service people stock the parts....I guess its a trades issue? Only HVAC techs could do the job, not plumbers?

 

[BoilerMan]

You are exactly correct, changing a refrigeration compressor requires; recovery of refrigeration, copper work, vacuum and recharging to proper amounts. This requires specialized equipment and certification to open any refrigeration system. Also certified (listed) equipment.

TS

 

[STIHLY DAN]

The geo spring uses 650 watts as a heat pump. In this mode around $100 a yr. When I have it hooked up to my Kuuma coils Tempering tank (80 gal) I get 3 showers a day with out the hp turning on. They have a 10 yr warranty. My oil boiler with tankless coil cost me $1,200-$1,400 a yr for hot water. So with no rebates, less than a yr pay off. But with my rebates, I MADE $350 to put one in. Works great, I love it.
In the summer with the dehumidification, I don't need to run the dehumidifier. So essentially It's like free hot water. I use hot water to brush my teeth in the summer, will pipe the toilets to hot water soon too. I want the hp to run in the summer.