Ground Source beats several Pros: Water remedy needed

[energy star]

Can you actually see a difference in the water flow direction? Why?

[beenthere]

jerrygr, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

You can find the rules for posting and qualifications here.

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[AC4AQ]

I suspect that is the answer right from the start has been to find someone with the proper qualification on this equipment. So far, we've yet to find her/him.

Since I last wrote, I found a valve which will accomplish the task of reversing the direction of the water flow in the coaxial heat exchanger and it did provide some meager but noticeable results. Not good enough to correct the problem though.

In cooling mode, reversing the water flow (discharge at capillary end) caused the head pressure to rise from about 190 psig to about 215, and a slight rise in the suction. In heating mode, with correct flow (discharge at caillary end) when the compressor starts the suction pressure steadily sinks for about 25 seconds until the low-pressure switch trips. After the unit restarts, the suction pressure again drops, but may stabilize at aroung 40 psig, then it gradually rises. When the system reaches stability, the suction pressure is around 62 psig, with a head pressure of around 205. With reversed water flow (as it was originally), the suction pressure sinks more rapidly and stabilizes at 55 psig. No temp reading yet on suction line to compressor, but not very cold. Also gas hisses loudly in heat mode only, not sure which line is noisy.

I hope I hit upon the means to find the right tech for the job, as the diagnosis seems to be difficulty. I'm hoping I can find a tech I can communicate with in advance, who will analyze the data and be able to say, "the reversing valve is sticking in heat mode" or some such thing and come with the wherewithal to do the job right the first time.

Thanks to those who have shared their knowledge. If you ever need advice on high-powered audio amplifiers from QSC, Crown Audio, etc, I'll be glad to reciprocate.

Jeff jHh

Lacking tha

AC4AQ, I too have had experience with Navy steam plants. Mine was gained while in the Navy Nuclear Propulsion program. That was years ago, 1979-1985, just prior to my entering the HVAC field, where I have spent 27 years in the commercial side of it. I lurk here in this forum, and residential forums, just out of curiosity, and the chance to learn. That knowledge and experience gained in the Navy has helped me over the years, but I would never use it over what I have learned in this field. Just as getting one small part of a heat transfer equation will definately give a wrong answer, assuming that different applications will respond similarily can be misleading. Especially when there may be unknown, therefore unaccounted for, differences. You are fortunate to have some of the more knowledgeable and experienced professionals here, who volunteer their services, helping you. You would do very well to heed their advice. I believe especially about calling someone who is experienced with your system.

[Brent Ridley]

Well, you managed to reverse the water flow and it didn't help. Wow, what a surprise. Several of us told you that it would not correct the issue @ hand.

What's the point in asking for advice if you don't take it? Or even consider it ?

It is almost impossible for us or anyone else to diagnose your system in advance. I listed some criteria above in my previous post that would help us "suggest" some possible issues with your system and I never got an answer.

Call around. Find a company that specifically services and installs geo thermal systems. One way to weed out possible "non-qualified" companies is to ask what brand geo thermal systems they install. If they don't install them, don't let them service your system.

[AC4AQ]

Can you actually see a difference in the water flow direction? Why?

Yes, there was a small improvement in performance in either mode by having the cooling/warming medium flow in the opposite direction of the refrigerant. It results in the difference in temperature between the two fluids being maximized along the entire length of the heat exchanger. For example, in cool mode the coolest water is in contact with warm liquid refrigerant leaving the coax, while the warmest water cools the hot gas exiting the compressor. If it were reversed, the water already warm from the heat of condensation would be in contact with the warm liquid, resulting in little subcooling.

In this case the difference seemed to be small as the heat exchanger seems to have a poor temperature approach. Likely in order to keep the retail price of the machine reasonable the heat exchanger is smaller than optimum, with the result that a large flow of water is necessary for reasonable performance.

In any case the faulty component remains unidentified. Likely the best answer is to scrap the unit as it is old.

jHh

[AC4AQ]

Thank you for your helpful reply.

It seemed to me that reversing the water flow was a reasonable plan as it agrees with the widely-published theory of heat exchanger operation and no one in this forum could point to any flaw in the my application of theory. It further seemed reasonable as it was doing something different. Calling yet another 'AC Professional' would be to do the same thing, and I've been told that to do the same thing repeatedly and expect different results amounts to insanity. Ultimately my test proved superior, in that it did produce small results for a small expense, whereas the AC Professionals were far more costly and produced nothing of value.

In any case, the best solution is to cut our losses and replace this defiant machine with something dependable, like a Franklin stove.

Thank you for your attention, I'll trouble you no more.

jHh

Well, you managed to reverse the water flow and it didn't help. Wow, what a surprise. Several of us told you that it would not correct the issue @ hand.

What's the point in asking for advice if you don't take it? Or even consider it ?

It is almost impossible for us or anyone else to diagnose your system in advance. I listed some criteria above in my previous post that would help us "suggest" some possible issues with your system and I never got an answer.

Call around. Find a company that specifically services and installs geo thermal systems. One way to weed out possible "non-qualified" companies is to ask what brand geo thermal systems they install. If they don't install them, don't let them service your system.

[crmont]

Am I reading this right? We're reversing water flow on a 40 year old unit?

May I suggest that there are two separate metering devices differentiated partially or completely by a check valve and a one way filter dryer.