Freezing heat pump coils

It is caused by a combination of temperature and humidity. To heat the coils in the house, the outside coils get cold which causes moisture from the air to freeze on them. A small amount of frost is normal but the heat pump should periodically defrost itself under these conditions before any substancial amount of ice can build up.

try to clean or wash up first your indoor coil unit,or the unit as a whole,filters etc,care should takes place if doing ourself.

im not as good with heat pumps but these in a little way can help.

also set your thermostat a bit lower n number.

thanks

Have the pressures checked. Most likely it is low on Freon (or whatever passes for freon these days).

Defrost cycle is not working for some reason. Try the above and check the thermostat on the unit. It senses the ice buildup and reverse the pump periodically to melt the ice and then returns to heating the house.

If this is uncomfortable for you to do, have it serviced.

2cents from

Brad

You have to remember exactly what you are doing, you are taking warmth from these coils (eg. cooling them down) and improving the quality (temperature) of this warmth for your house to warm it up.

If the outside temperatures (and humidity) are such that this cooling takes the coil now below the freezing point, ice will form and effectively insulate the coil......

Possible fixes:-

1) a larger or longer coil - see this as similar to fishing net size, but fishing for heat, a bigger net capture more fish (heat)!

2) Place in a better area where say the sun gets to it earlier in the day.

3) Defrost cycle (which uses your heat energy) needs to be used more often....

4) place in an area where the supply of heat is simply far greater. I had a friend who laid a huge plastic (underfloor heating pipe) under his lawn, it works and supplies a heat pump for heating and hot water the whole year round, day and night, except when snow lies on the ground!!!! Then he heats with gas!!! It has been in use over 20 years.....

5) Accept that you cannot get such heat 365 days a year and add a boiler......

Since the original post indicates that the system worked at one time, try not to re-engineer the whole system unless that is what is called for. If there have been no substantial change to the building that would add more load, then re-engineering the system should not be needed. Most likely there is a control problem involving the defrost system, but at five years of age, a good cleanig and servce out is going to save money in operating cost and in equipment life. -- JHF

Either the defrost timer/freeze stat isn't working or the reversing valve or the valve control has failed. Or check for gas leaks and recharge the system.

The method used to defrost the coil is to redirect the hot gases to the outside coil (condensing unit) from the inside coil (DX coil) thereby defrosting the coil. This takes a small amount of heat out of the house and uses it to defrost the coil.

In the interm, you can manually control this by switching your thermostat to cooling making sure to lower the temperature for a few minutes and see if this works until you can get the unit serviced.

"In the interm, you can manually control this by switching your thermostat to cooling making sure to lower the temperature for a few minutes and see if this works until you can get the unit serviced."

Thanks for the suggestion. I'll try it the next time it freezes.

I have located the temperature switch on the outdoor unit and have a wiring diagram for the system. I can check the switch state (on/off) from indoors. Beats going outside and tearing into the unit.

That's not going to work unless he knows how to pull the electrical cover off the outdoor unit and yank the condenser fan motor wire off of the defrost relay . The outdoor fan will cool any heat brought outside.

If he is brave enough to pull the cover, maybe he's brave enough to touch the defrost test pins and see if it engages defrost AND clears the coil. Maybe he's REALLY brave and borrows some manifold guages and a thermometer and checks his superheat and sub-cooling and compares it to the mfr's chart for performance at his given outdoor temperature.

If he's on a real "roll", maybe he'll pull the cover off the indoor cabinet, put the system in emergency heat, fire up the strips, measure amps and volts, stick his calibrated thermometers in the supply and return ducts, record temp rise and then calculate system CFM and write it on the ductwork for future performance testing, (after he changed the filter and cleaned the coils of course). THEN... he's ready for a 10 minute heatpump compressor run where then he'll again take exact temperature rise measurements, calculate the heatpump's ACTUAL btu output and compare it to the manufacturer's integrated heating capacity chart.

I doubt he'll do any of the aforementioned.

Best thing to do is have it checked by a competent serviceman.

"Best thing to do is have it checked by a competent serviceman."

And herein lies the problem. Where does one find a competent serviceman?

The clowns that put the system in wouldn't have a clue as to how to do all the stuff you recommended.

And herein lies the problem. Where does one find a competent serviceman?

YOU....have an excellent point there ! And that is sad to say

( I'm replying to you, but the original poster has the problem), in the yellow pages or if the HVAC company's have a web-site, look for them to proclaim they have NATE certified technicians. ( There are other good programs out there too but that one IS good.)

The other thing to try is looking up a contact number from the manufacturer and plead your case about not finding a competent serviceman, they'll steer you toward someone good if they offer any names at all.

I agree 100% about not being able to find a competent service person. I searched for over a year and fought with a few problems. Check out the picture of my frozen unit.

http://www.schmooseme.net/payne-in-the-ear.htm

I will never recommend a heat pump to anyone in the northern part of the county. I'm south PA.

RSC