Check your furnace filter

[harringtondav]

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.

 

[BWR1953]

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]

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]

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]

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]

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]

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]

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.

 

[Renken2000Classic]

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]

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.

 

[Renken2000Classic]

I got some unwanted time with my indoor unit today - like all day off and on, changing the blower motor and then cleaning at the indoor coil and unclogging the condensate drain - and I confirmed that there is no filter in the furnace itself.

It's an upflow style, with a side return, right into the blower.

Man it was nasty in there. Rather a shame. And brutal in the attic with an OAT near 100F. I had to give it up for a while in the afternoon. Even though it was in the 80s in the house by then, if felt pretty good compared to that.

 

[harringtondav]

I got some unwanted time with my indoor unit today - like all day off and on, changing the blower motor and then cleaning at the indoor coil and unclogging the condensate drain - and I confirmed that there is no filter in the furnace itself.

It's an upflow style, with a side return, right into the blower.

Man it was nasty in there. Rather a shame. And brutal in the attic with an OAT near 100F. I had to give it up for a while in the afternoon. Even though it was in the 80s in the house by then, if felt pretty good compared to that.

Filter boxes are available in a variety of sizes. Your return may allow one to be inserted, with some modifications. A trip up into the attic sounds like a pain to change a filter, but less painful than what you just went through. Possibly there's a more accessible location in the main return?

 

[Renken2000Classic]

I've got 2 returns in the ceiling, and there's a filter at each. Obviously they didn't catch everything though.

After all that, after running for several hours straight last night, the sound level through the returns increased noticeably, lol. So something's not exactly right now. I can't tell by looking at/feeling the blower housing with it running (and I can't really hear it with the door off and lookng at the blower), but when I put my hand on the side of the box with it all buttoned up, I can feel rapid light pulsing (like something's out of balance).

It was just a simple direct drive motor swap, with nothing to mess up really, so I would suspect the motor itself (Century, replaced the original GE). Possible it's some other item vibrating in the airstream, but doesn't seem like it.