Check your furnace filter

harringtondav

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Simple, inexpensive maintenance can save you a lot of headaches.
Yesterday I noticed the new heat pump split system at our river house wasn't keeping up. It was running on back up electric heat strip. I checked the power going to the heat strip and found it was only drawing 1/2 current. Momentary panic. Then I remembered that I'd been generating a lot of drywall dust from a basement finish project. New filter and all was well. The clogged filter forced the heat strip into low power mode to avoid burning up. So check and replace your furnace filters often. Filters are cheap.

IMG_20220218_074336924.jpg
 

BWR1953

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Yup. Same situation with our AC filter here. Last year when I was installing the new driveway, there was lime rock dust everywhere. The house wasn't cooling like normal and we discovered that the AC filter was seriously clogged even though it was less than a month old.
 

harringtondav

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Yup. Same situation with our AC filter here. Last year when I was installing the new driveway, there was lime rock dust everywhere. The house wasn't cooling like normal and we discovered that the AC filter was seriously clogged even though it was less than a month old.
Another simple maintenance job on a central a/c condenser unit is to pull the power, remove the top cover and gently spray a garden hose at the condenser coil fins to back flush the dust/debris that will accumulate. I do this every few years. The first time I learned to do this there was a 1/8 thick mat of dust. The register cold air temp (delta T) improved by about twelve degrees.
 

BWR1953

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Another simple maintenance job on a central a/c condenser unit is to pull the power, remove the top cover and gently spray a garden hose at the condenser coil fins to back flush the dust/debris that will accumulate. I do this every few years. The first time I learned to do this there was a 1/8 thick mat of dust. The register cold air temp (delta T) improved by about twelve degrees.
Yah. BTDT. 😏
 

440roadrunner

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What you have posted here is FAR worse that just a lack of heat. If the heat pump is running under reduced air conditions (in heat mode) the head pressure/ temperatures will be very high. This is very hard on the compressor and will contribute to short life. One of the banes of heat pumps is poor ductwork design and not enough airflow.

I did HVAC/R service in the 80's ---mid 90's for a little over a dozen years. I have not kept up, but there surely are air pressure monitors for filters. Or just make sure you change them LOL And clean the coils occasionally.
 

Sprig

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Changing filters at certain intervals should be a routine (yes I know depending on conditions you may need to replace filter sooner than what ever your normal interval is). When I replace a filter I mark on the side of the filter the date I replace it and I also put a small piece of tape with the date outside the filter compartment. Finally I mark the date on my iPad electronic calendar which notifies me when it needs to be replaced.
I was talking to an HVAC guy who told me how often he goes on service calls and the problem turns out to be clogged filter that hasn’t been changed in years. Changing the filters is cheap and easy and the uni5 will last way longer.
 

harringtondav

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Changing filters at certain intervals should be a routine
When I replaced our home gas furnace (and 3 T condenser) a few years ago, the tech suggested using cheaper air filters and changing them more often. I'd been using expensive Filtrete allergen level filters. I understand his logic. Buy the time an expensive filter is spent it's been blocking airflow for some time. The less expensive filters work OK for us....no allergies, and can be replaced more often at no cost penalty, and keep average airflow and delta P closer to optimum.
 

harringtondav

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What you have posted here is FAR worse that just a lack of heat. If the heat pump is running under reduced air conditions (in heat mode) the head pressure/ temperatures will be very high. This is very hard on the compressor and will contribute to short life. One of the banes of heat pumps is poor ductwork design and not enough airflow.

I did HVAC/R service in the 80's ---mid 90's for a little over a dozen years. I have not kept up, but there surely are air pressure monitors for filters. Or just make sure you change them LOL And clean the coils occasionally.
Thanks. I was sweating the heat kit, but at least it has high temp limit switches....that worked this time. The kit has two elements and I'm guessing the top one was the one that shut down.
I forgot that the evaporator (condenser in HP mode) needs to shed its heat also. I have a second filter taped to a cut out basement return during the drywall work. I'm buying a half dozen more filters and will be changing them weekly until the dust settles.
 
Joined
May 10, 2022
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When I replaced our home gas furnace (and 3 T condenser) a few years ago, the tech suggested using cheaper air filters and changing them more often. I'd been using expensive Filtrete allergen level filters. I understand his logic. Buy the time an expensive filter is spent it's been blocking airflow for some time. The less expensive filters work OK for us....no allergies, and can be replaced more often at no cost penalty, and keep average airflow and delta P closer to optimum.
I can't even use the more heavy duty ones, or my system seems to cycle on the limit (gas heat). I have a semi-odd size and have not always been able to find the cheap ones easily; that's how I found out.

Another Q re this, is do you know where all of them are? There may be one hidden in the indoor itself, not just the return air registers. I think my last house was like that...
 

harringtondav

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2,119
I can't even use the more heavy duty ones, or my system seems to cycle on the limit (gas heat). I have a semi-odd size and have not always been able to find the cheap ones easily; that's how I found out.

Another Q re this, is do you know where all of them are? There may be one hidden in the indoor itself, not just the return air registers. I think my last house was like that...
I only know systems that have the filter at the air handler/furnace. None in the return air system upstream.
Check you entire system for filter locations. Returns and the main air box. If your high limit switch is shutting you down you may have blocked air flow...return or supply. Make sure all supply registers are open. Also your high limit switch could be failing. Most HVAC systems have a decal or OM page showing the safety switch string.These are cheap in the big picture. ...many "appliance pros" and other web sites have these. ....get your furnace model and s/n. Or remove it and take it to a Dey Appliance Parts store or any other.
 
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