DM not DIY

[ptonsparky]

I noticed it was a bit chilly in the house this morning. 64 degree air from registers instead of 75 or better. Code indicated thermistor, water flow & a couple other things. HP was going into lockout.
Chart indicates resistance of thermistor at xxx degrees. Mine showed about 13k ohms which put it in the 60 degree area. Close enough.
Do they fail such that it would be good at 60 and not at 40or 70?

 

[Little Bill]

I noticed it was a bit chilly in the house this morning. 64 degree air from registers instead of 75 or better. Code indicated thermistor, water flow & a couple other things. HP was going into lockout.
Chart indicates resistance of thermistor at xxx degrees. Mine showed about 13k ohms which put it in the 60 degree area. Close enough.
Do they fail such that it would be good at 60 and not at 40or 70?

I think you have left out part of the story, I feel like I walked in half way through the movie!

Starting with.. what does "DM" mean in the title
What type of heating?
What is this code you speak of?
What is the chart?

 

[kwired]

I think you have left out part of the story, I feel like I walked in half way through the movie!

Starting with.. what does "DM" mean in the title
What type of heating?
What is this code you speak of?
What is the chart?

Not sure on DM.
Sound to me like most likely a geothermal heat pump
Code is error code on the controller
Chart is troubleshooting chart of some sort that tells what resistance should be at different temperatures.

Tom - no backup heat, or did you have it disabled?

I've disabled my backup heat before, if you don't you might not even know for some time that the heat pump isn't working (except during cooling season of course).

 

[ptonsparky]

Diagnose Myself not Do It Yourself. I wanted know what failed.
Pump & Dump water to air Heat Pump. Bryant alias Carrier.
Read the manual to find how to read the fault code. Code 4. Lockout.
One of symptoms of that code is a bad temperature sensor. A thermistor.
Again RTFM paid off with how to check the thermistor. A table gives me the thermistor resistance at whatever temperature it might be at.

 

[kwired]

Diagnose Myself not Do It Yourself. I wanted know what failed.
Pump & Dump water to air Heat Pump. Bryant alias Carrier.
Read the manual to find how to read the fault code. Code 4. Lockout.
One of symptoms of that code is a bad temperature sensor. A thermistor.
Again RTFM paid off with how to check the thermistor. A table gives me the thermistor resistance at whatever temperature it might be at.

Most common lockout reason on mine is no water for some reason. Might be thermistor that triggers lockout but I'd bet you had water flow issues for some reason and that made it lock out. If not thermistor you maybe lock out if it monitors refrigerant pressure. Next most common thing for lockout might be if you had plugged air filter or left the front cover off the unit and it wasn't pulling air over the coil, or some other reason air not getting over the coil - blower motor could have failed also, and per my other question would also not give you any back up heat if that happened.

 

[ptonsparky]

Not sure on DM.
Sound to me like most likely a geothermal heat pump
Code is error code on the controller
Chart is troubleshooting chart of some sort that tells what resistance should be at different temperatures.

Tom - no backup heat, or did you have it disabled?

I've disabled my backup heat before, if you don't you might not even know for some time that the heat pump isn't working (except during cooling season of course).

The backup heat was working fine. We set back to 64 at night then up to 69 during the day. 12 degrees out this morning so it was taking a while to warm up. First stage backup was just enough to keep it from kicking the second stage on. I could hear both stages of the HP running water when I went down to investigate. Unfortunately that water running does not mean the compressor is on. Something I did not know. I will fix that.

 

[kwired]

Most common lockout reason on mine is no water for some reason. Might be thermistor that triggers lockout but I'd bet you had water flow issues for some reason and that made it lock out. If not thermistor you maybe lock out if it monitors refrigerant pressure. Next most common thing for lockout might be if you had plugged air filter or left the front cover off the unit and it wasn't pulling air over the coil, or some other reason air not getting over the coil - blower motor could have failed also, and per my other question would also not give you any back up heat if that happened.

Though it hasn't been that cold so far, I've had lockout when discharge line froze near it's outlet in the past (I have pump and dump also, it dumps out in shelter belt behind the house). This seldom happens as it never is in an off cycle long enough to freeze, especially when really cold outside. But can happen if power had been off, or system just had not run long enough for it to freeze for whatever reason.

 

[ptonsparky]

FWIW. Two stage heat pump, two zones, and at least two banks of backup. Maybe three.

 

[kwired]

The backup heat was working fine. We set back to 64 at night then up to 69 during the day. 12 degrees out this morning so it was taking a while to warm up. First stage backup was just enough to keep it from kicking the second stage on. I could hear both stages of the HP running water when I went down to investigate. Unfortunately that water running does not mean the compressor is on. Something I did not know. I will fix that.

Did you reset it and see if it runs? Might not know what really happened unless it becomes persistent at doing it.

 

[kwired]

FWIW. Two stage heat pump, two zones, and at least two banks of backup. Maybe three.

Haven't seen a Geothermal myself that wasn't two stage compressor, but is usually only single stage of backup control wise. Most are usually ~10 or ~15 kW backup. Friend of mine installed lot of them around time I did my new house about 15 years ago. Recent years he hasn't really sold any, gas went down enough people rather have that right now. Even if Geo is more efficient, install cost for ground loop is the deal breaker. Not sure if I'd do pump and dump again. Seemed good when we installed it, but I spend lot of $$ over past 15 years on well issues that wouldn't happen if not pumping so much water all the time.

 

[gadfly56]

Haven't seen a Geothermal myself that wasn't two stage compressor, but is usually only single stage of backup control wise. Most are usually ~10 or ~15 kW backup. Friend of mine installed lot of them around time I did my new house about 15 years ago. Recent years he hasn't really sold any, gas went down enough people rather have that right now. Even if Geo is more efficient, install cost for ground loop is the deal breaker. Not sure if I'd do pump and dump again. Seemed good when we installed it, but I spend lot of $$ over past 15 years on well issues that wouldn't happen if not pumping so much water all the time.

Pump and dump is a new thing to me. I'm not sure NJ would let you discharge water to the surface, or tap the aquifer for so much flow. About the only thing you can do here, IIRC, is a closed loop system, or an air coupled system with pipes in the ground.

 

[kwired]

Pump and dump is a new thing to me. I'm not sure NJ would let you discharge water to the surface, or tap the aquifer for so much flow. About the only thing you can do here, IIRC, is a closed loop system, or an air coupled system with pipes in the ground.

We have probably largest underground water supply in North America, maybe even the world, under most of NE and part of why we are the king of center pivot irrigation machines though the exist here and there in the rest of the world, but those others were probably made here.

Some those "waste" more water than my pump and dump system probably does.

In warmer weather months I can divert mine to lawn watering, but need to make sure to not restrict it with whatever you do here. Too much restriction will starve the heat pump of water it needs and result in "lockout" and house not being cooled.

 

[ptonsparky]

I’ve noticed it a bit chilly but by the time I get back home it’s good enough. My significant has not complained.

The bitch of it is pumping all that water and having it do me No good.
There is an alarm relay that closes on lockout and I do have a PLC that texts me for other stuff. Just as well have it do another

Turned the E Heat on. $$$$$, but I‘m warm now.

 

[kwired]

I’ve noticed it a bit chilly but by the time I get back home it’s good enough. My significant has not complained.

The bitch of it is pumping all that water and having it do me No good.
There is an alarm relay that closes on lockout and I do have a PLC that texts me for other stuff. Just as well have it do another

Turned the E Heat on. $$$$$, but I‘m warm now.

Can't reset the "lockout"? Think mine will reset if you turn thermostat down or off so that you interrupt all demand for heat. Otherwise it definitely does if you recycle main power. Might need to run for a bit before it locks out again depending on what is making it lock out.

 

[ptonsparky]

Soft reset is when the stat cycles. Hard is power off. The compressor runs again at each start, then lockout again. I had gauges and experience back in the days of R22.

I'll let you know how much more heating air techs cost than I do

 

[WasGSOHM]

A thermistor is not complex and if it works at one temp I can't imagine it going way off at other temps.

Maybe it's a forward-biased-diode where temp vs. voltage drop at a constant I is a straight line, but same comment about way off. It should change at -2.2 mV per degree C.

 

[kwired]

Soft reset is when the stat cycles. Hard is power off. The compressor runs again at each start, then lockout again. I had gauges and experience back in the days of R22.

I'll let you know how much more heating air techs cost than I do

Guessing it runs only few minutes at most? Has to be either refrigerant system issue or heat transfer issue (probably more like lack of transfer).

Another thing I guess that is possible during heating mode is if there isn't enough water flow it will likely lock out to protect from freezing the water in the evaporation coil. Maybe check temp differential in the water lines. I think ideal flow rate is supposed to give you somewhere around 10-15 degree drop in water temp, but may be at risk of lockout if outlet gets much below 40.

too much water deposits in that heat exchanger can also make it cut out or lock out on refrigerant pressure if heat transfer is reduced too much. I think there is methods of flushing that out, but not sure how much of a process that may be. Would think it involves acid solution and recirculation possibly multiple times.

 

[ptonsparky]

There is ample water flow. More than enough in my thinking As the temperature differential has never been in the 10-15 degree range. The water is filtered before the HP. Filter is clean.

 

[kwired]

There is ample water flow. More than enough in my thinking As the temperature differential has never been in the 10-15 degree range. The water is filtered before the HP. Filter is clean.

I was getting at hard water deposits could be effecting heat exchange.

15 degrees might be a little much, but really depends on incoming water temp. IIRC when setting mine up we were wanting about 10 deg when running on both compressor stages in heating mode. Less than that means you are pumping more water than you need to which creates less efficiency elsewhere but still related to operating your heating/cooling system. If you think about it these systems work pretty good at extracting heat in an air to air system down to at least 10-15 degrees, no reason they can't be even more efficient extracting heat from water as long as it doesn't extract so much heat that it freezes the water in the heat exchanger. Getting much below 40 with outlet water might be cold enough that it can start to form ice on the heat exchanger walls.

 

[Russs57]

Do you have a schematic? If you could work on a R22 system nothing is different, just a different pressure for a given temperature.

See how many amps your compressor is drawing. See if the unit appears to be working correctly for the few minutes it will run. Check and see if you have a pressure switch that is taking you out. If your amps are reasonable and refrigeration lines feel okay in temp I’d have no qualms bypassing a pressure control to get me out of trouble.

A lot of units nowadays have all the sensors as inputs to a board and those boards like to go bad. If you know controls you can generally put something together with off the shelf parts.

Good luck.