Water sourced heatpump cycle?

[smoss]

Slow? Two txv's! Maybe reverse valve.

I have two TXV's? I don't know. I thought the reverse valve only stays in one position mostly.. until you change modes heat to cool.

I haven't used cooling mode much but from what I have seen it doesn't trip in cooling mode at all. Maybe you were getting at one TXV for cool and one for heat mode? I am no expert just trying to help the HVAC guys before their next visit.

[timjimbob]

HP uses two "expansion devices". TXV or equivilant is florator or maybe cap tube. One is for heat, the other for cool.

[smoss]

HP uses two "expansion devices". TXV or equivilant is florator or maybe cap tube. One is for heat, the other for cool.

Thanks.

After the heat was off for a few hours, I came home and turned on cool mode. It didn't trip. So it looks like the issue is only with heat. I would guess it's probably a slow TXV, or metering device, in heat mode only.

Looks like Mammoth is working on sending a new control board (that they previously said this unit doesn't need). I guess they would rather delay than mess with the TXV. Not sure. Either way, I guess it will solve the problem.

[smoss]

Hate to bring this thread up again but it is still not fixed. The HVAC guy was here all day Thursday last week. The manufacturer is now paying for all this work. They told him to drain the water line, and connected two balloons on the input and output of the water connections. The thought is, if it is leaking refrigerant it would leak into the water lines and fill the balloon. After an hour or two it looked like the balloons were expanding but after about 4-5 hours the balloons were actually sucked in. HVAC guy attributed that to pressure change when cooling down. The conclusion is, the heat exchanger is not leaking. He couldn't find any leaks using an electronic sniffer.

I asked about pulling out the refrigerant and weighing it to really be able to tell if it had lost any. He said Mammoth is paying for this and they had not suggested it. He also said he could pump it with Nitrogen and see if it leaks or fill it with dye. He also told me Mammoth admit they had known heat exchanger problems in 2010. If a leak had been found, they were going to change the heat pump no charge. So now we are awaiting their next move.

They might come back with a delay board to be installed but the delay has never been needed on this heat pump model according to Mammoth. They have to figure out how to wire it up and get back to the HVAC guy. Seems strange that only my heat pump would need this delay. I am thinking it could still be leaking and the new delay board will only work for a few months while it still leaks.

I have been running the heat at a high temp of 75 (high for me) and letting it run as much as possible. If it is going to leak out I want it to leak now so hopefully it gets fixed before the board gets installed. It seems like it is a little worse in the last day but hard to say. I know yesterday it had to try twice before it actually kept running and I have never remember that happening. It always starts 4 minutes after it trips. Perhaps I am making it worse. Not sure. I intend to leave the heat raised at 75 all day tomorrow while I am at work so hopefully it leaks out and I have no heat by Wed. If it's a small leak I suppose it could take months to leak out enough to force it not to start. Not sure though. This temperature is killing me though. I hate it this warm.

This problem has been going on since I moved in last October. Very frustrating!

[beenthere]

Wouldn't have taken long to recover and weigh. He really didn't save Mammouth anything by not doing it.

[smoss]

Sorry revive this thread..... more problems it seems. I am looking for some help in deciding to call the guy back or not.

So the original problem with my heat pump was a low pressure cut out the first time the heat started up. It was determined that the heatpump is probably not leaking. A full factory charge was put in January. The fix was to put a 20 second delay in place that basically ignores the signal from the low pressure cut out switch. Heat worked fine after that... looks like problem solved. He didn't weigh out the charge but looked at pressures and said it was right where he left it in January... this was about 2 months ago.

So now.... I have used AC mode a few times in the last few weeks. It was very rainy last week. AC set to 73. I noticed that the humidity kept rising every time AC was operating. I also noticed a musty basement type odor coming from the vents. Humidity would be low 50's and rose to almost 60% as AC ran. I shut AC off for a few hours and it would fall a bit until next time AC kicked on (temperature only rose about 2 degrees within that time). I checked drainage hose and it looked to be draining. Ducts are not in a basement or anything they are in between the floors of each apartment.

So, I decided to measure the return temp and the supply temp. The return temp was 74 and the supply temp was only 62. I measured it a few days later (when the rain had stopped) and same thing. Only about a 12 degree temperature drop. I thought that meant there was an issue. Should I call the HVAC guy back? The apartment cools fine and only runs for 5 minutes but it's only in the 70's out. Now that it is drier out, there is no odor and seems to be working great. I would rather not wait until we hit our first 85 degree day to have a non functioning heat pump. Is it something not draining properly or perhaps it is in fact leaking and this was the problem all along. The HVAC guy did say it's possible it only leaks charge in cooling mode. They have been playing with the charge of this unit for the 3 years since it has been installed (before I owned the place). There was talk about Mammoth replacing the unit.

Any thoughts would be greatly appreciated. I would hate to call the HVAC guy if I am being overly concerned. They have spent several hours (multiple trips) to my place to fix the original problem. I thought I was past this. Maybe I should wait until I have no AC to call them?

[beenthere]

Did you check the temps at the unit, or at registers.

[smoss]

Did you check the temps at the unit, or at registers.

At the registers. The supply register I used was furthest from the unit. I wasn't thinking there was much temperature delta in the ducts since they basically run just above my ceiling below the floor above me. If it helps, the return and most supplies are metal ducted. Some supply are insulated flex running from there.

The heating mode (measured at same ducts) was about 18 degree temperature rise when I checked months ago.

[beenthere]

You can lose or gain temp even in a set up like yours, so its not accurate enough.

[smoss]

You can lose or gain temp even in a set up like yours, so its not accurate enough.

Beenthere, thanks for helping!! I just got home. Temp in apartment was 73, 70 degrees outside not much sun coming in. I lowered the Tstat to 70.

I measured a supply vent in my bedroom. The heat pump is above my master bathroom. The total supply for the heat pump runs into a big distribution box (don't know what to call it) then the flex vents run immediately to my bedrooms. The metal duct runs further to the living room where I measured previously. The bedroom vent is as close as possible to the heat pump.

I just measured both supply vents and they are giving me 10 to 12 degree temp drop. I say 10 to 12 because the temperature was dropping in the apartment. The AC ran about 10 minutes and clicked off since it was now 70 degrees in here. So it is obviously cooling but it's not hot outside.

Granted I am simply measuring with a hand held thermometer against the vent which is not the most accurate, but I was able to get 20 degree temp rise using this same method for heat last winter. Over the weekend I was getting 15 degree temp drop with the AC, now 10 to 12 at same vent. I guess if it is leaking it will get worse in the next week or so. I'll wait another week and see. I'll run the AC every night to force the issue.

You know luck will have it that it goes out when we hit 85 degrees when the HVAC guys are the busiest!!

Oh, the Tstat is directly under the return. When I measured the return it matched the Tstat very well.

[beenthere]

Yeah, should be a higher differential then what your getting. If its leaking, it will just keep getting worse.

[smoss]

Update.

Guy was here this morning. He said super heat was high, pressures were high. Cooling temp diff was low (12 degrees). He tried adjusting TXV but couldn't get it to change. TXV worked fine few months ago and super heat was also to spec then. He said it's possible refrigerant leaked out and he can't add more flow because there is none to add. He said it is strange pressures are high if it's low on charge. Not sure. He did remove top of TXV and look at the bulb and spring.

They decided to warranty the unit. They will be replacing the entire heat pump

They have been messing with this unit ever since it was installed (2011). I noticed even the previous condo owner had them come out. If the unit was good to start they would have never had to mess with it I think. Add some, remove some, adjust TXV, add time delay (original subject of post). Only issue is, I have to pay labor on the new one!! I haven't paid anything up to this point so i guess it's fair. Still not happy. At least it should be problem free afterwards.

[beenthere]

Glad to hear they are going to replace the unit for you.

[smoss]

Glad to hear they are going to replace the unit for you.

Thanks. It will be good to have this behind me!!

One more question. It seems the heatpump has 3 fan settings. My current one was left on high... I think they just leave them on high upon install. I asked him about lowering it to medium on the new install I have a 3 ton heatpump, two returns, and very short ducts. Maybe 8 kinda large supply registers. The air that comes out of those vents is immense. I can feel it blowing 15 feet away and the noise is medium. Compared to my parents new home in SC I can't hear that one at all and I only feel a gentle breeze when it's running. It's rather nice.


What is the purpose of having an adjustable fan if nobody adjusts it? If adjusting it to medium means he has to adjust the charge then I'll leave it I don't want anyone playing with the factory charge. The guy said he can adjust it but he seemed hesitant.

[beenthere]

If it has a TXV, no need to touch the charge. Good chance that even if it has a piston, the charge is fine.

The fan has speed taps to adjust it for the duct work system's conditions. But lots of installers don't bother changing it from factory default.

[smoss]

I am afraid I am back again. The companies are arguing about replacing the heatpump. Not sure what will happen. I am not sure the HVAC guys can do diagnostic work. They simply check pressures, measure sub cooling and that's it. I don't think I can go to another HVAC company since the condo building has a contract with them for all 75 apartments. They have looked at this thing about 8 times in the last 6 months.

In a nutshell this is where we are at. The original heating mode problem seems to be fixed.. although it was a bandaid fix by adding a delay circuit on the low pressure cut off switch. That works. At that a point the unit was pumped down and a factory charge put in. Sub cooling matched specs in heating mode.

Now, I am in cooling mode and temp delta between supply and return is about 12 degrees. As you can imagine there is a lot of humidity in the air. The HVAC guy checked and the sub cooling is now way off. He tired adjusting TXV to allow more refrigerant but it is wide open and nothing changing. He thought it was low on charge now (ie. leaking) but he said the high pressure is ok. He didn't want to pull out the charge and weigh it but I can ask again. The temp delta is still around 12 degrees and it has been several weeks. So maybe not leaking.

So, my question is..... he installed this unit in 2011 and I know for a fact that the fan speed is set to high. Is it possible all these issues since the install is because the fan is too high???? I know slowing the fan will help but not sure if it's the source of the problem.

I thought the 3 fan taps on the heatpump are simply for comfort settings or could they explain the issue? In other words, if I take a new heatpump and set it up on a bench with no duct work, turn it on high fan speed, will the sub cool and delta T all match what they should? Does that fan speed have to be adjusted for proper operation? I know the fan speed changes a lot of the parameters from reading on this website but not sure if it explains my problem enough.

I can tell you it's a 1400 sq ft. apartment, 3 rectangular wall supply vents and about 6 ceiling vents. They are all open. The air coming out of the vents sounds like a hurricane. Air can be felt 30 feet away.

Any thoughts? How would you guys debug this problem? I now some said weight out charge. Can it be leaking with high side pressure ok? Any help would be appreciated as I want to help point him in the correct direction possibly.

[timjimbob]

I an familiar with condo asso. If you are stuck with one company, It is time you attended a board meeting and demand that another company check this out. It may be better that you not tell the other company a thing except the appartment gets hot during the day. Only tell them some one else has tried to figure it out, but let new company come to a conclusion.

[smoss]

I an familiar with condo asso. If you are stuck with one company, It is time you attended a board meeting and demand that another company check this out. It may be better that you not tell the other company a thing except the appartment gets hot during the day. Only tell them some one else has tried to figure it out, but let new company come to a conclusion.

If it doesn't get replaced, I'll give them one more try. They have been very good to me so far. Have only charged me for one service visit even though they have been to my place a bunch of times.

The apartment isnt' getting too hot. It can easily reach temp. I set it to 68 at night and it easily gets there. Of course outside temps are only in the 70's but even when it's 85 outside it can reach temp. It rarely gets into the 90's all summer here. I suspect it is very oversized because last winter even with -20F outside temps, the heat only ran 10 minutes or so. The same HVAC company chose the replacement size of 3 tons. I am hoping this is not unfixable just because it's oversize... but he did say sub cooling was off and temp delta shouldn't be 12 degrees for a 3 year old heatpump.

[smoss]

Hate to have to bring this thread up again!!!

My heat pump was changed in June last year. I paid labor unit was warranty. It ran in cooling all summer no issues whatsoever. I recently activated heat. It runs for one minute then shuts down. Installer came out and said pressure is falling too low. He disabled the low pressure switch and let it run for 10 minutes. Pressure never went above 95. He said it has to go above 100 before the pressure switch would stay engaged. So on this unit no amount of delay is going to fix this... unlike the last heat pump that went above 100 after about 1 minute.

So.... they don't want to work on it at all. They said all the trouble shooting on the last unit wasn't reimbursed by Mammoth and they lost money. They are asking that I work with Mammoth directly since the unit is under warranty. He assured me the water flow and temp delay of the water loop is fine. Delta T of 5 degrees and plenty of flow. So now I am waiting for Mammoth to contact me. In cooling mode pressures are perfect.

In the mean time, he left the low pressure switch deactivated. I asked if it was problematic to run it this way and he said you wouldn't want to run it that way all winter. He said it could freeze up in cooling mode which I probably won't be using. Is it bad to run it with low pressure switch disabled?? The unit doesn't sound very good when it's running. I would just assume run a small electric heater until this thing gets fixed if there's a chance I can damage something. Thoughts? I am really getting very frustrated at this point.