Underlying Problems That Get Missed

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I ran a service call today with another tech where the previous tech had diagnosed an intermittent piston restriction. I read the history beforehand and for the past several years there were a lot of assorted comfort complaints and lot of little charge adjustments in both the Summer and winter, it is worth noting here the system, like many in our market this system a heat pump.

There were mentions of freeze-up during the Summer and high pressure cut out during the Winter which had me thinking airflow even before we arrived.

As we pulled up I noticed it was a townhome community with four homes per building.

There was no tenant home so we accessed the home via lockbox and as we walked up the stairs I was noticing the home was quite small… two bedrooms and two baths and when we opened the air handler closet it was….. 3.5 tons

The place had 12″x12″ tiles on the floor and it was a simple rectangle so we counted up length x width and the entire home was just under 1200 sqft.

Now sqft per ton is no way to do a load calculation… I admit it

But this townhome had occupied spaces on both sides meaning the only exposures and windows were on two sides with big trees shading the back, the building was built in 2007 and this system was installed in 2016.

What’s the next move you would make?

Common Sense

The great thing about having 4 other, almost identical units on the building is that we can easily see what tonnage they had installed, and they were 2-ton units…. makes more sense.

So in 2016 some fly-by-night company hacked in a 3.5-ton unit rather than using a 2-ton that may have been a little oversized to begin with given the low loads on this home.

The result is a system that is running REALLY low airflow resulting in low evap temperature and low superheat in the summer and high head pressure in the winter. Techs had been trying to “fix” the problem each year with little charge adjustments rather than finding and fixing the underlying issue.

After walking around the home we found some vents closed… likely because they were blowing somebody’s wig off with the high air velocity.

We went in the attic and found some ducts unsealed, some insulation pushed out of the way and two bath fans venting freely in the attic.

None of this required fancy tools or advanced diagnostic techniques to diagnose… just some common sense… some looking around and a little comparison to figure out the story.

Elementary my dear Watson… Elementary

— Bryan

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