Have a buddy buying a 1950's era home in Houston.

Was getting the HVAC inspected and the tech is saying that the tonnage is way too large for the home.

I don't think he's totally wrong, as it's a 5 ton (single stage) system for a 2,000 sqft (1 story) home, but I'm also thinking it's not insulated super well, because of the vintage.

Question is, how big of a deal is this going to be? I'm assuming it will cool the home down too quickly, before it can pull all the humidity out.

Is the delta large enough that he should consider replacing the condenser?

My 1970 casa is ~2100 sf and also has a 5 ton unit. It's nice on blistering hot days but the unit doesn't run long enough on cooler days to pull much humidity out of the air. When we bought the house it had old single pane aluminum windows so the AC definitely worked harder. Now that we've replaced windows and some exterior doors it's got me looking to swap thermostats to something that will let me adjust the set temp delta before it kicks on and off. It's not a big enough problem that it's an urgent fix but I'll likely downsize when it's time to replace the unit.

thanks. that's helpful.

They have the double-pane as well (but they're probably 15-20 years old).

Tell him to ask the inspecting HVAC company to do a Manual J calc to determine the appropriate size. Anyone guessing on sizes without taking a closer look at things like insulation, windows, exposure, etc. is just spitballing.

The outdoor condenser is a single stage, but is it paired with a variable speed furnace or air handler (blower in attic)? He may be able to dial back the CFM from the standard 400CFM/ton to 350CFM/ton using the dip switches. Even better, he may be able to have the blower act as a multi stage unit to reduce humidity and increase comfort. As example:

I don't know that the blower in the attic is variable speed.

You may have exceeded my limited knowledge of HVAC.

If the unit is way oversized, maybe keep it for those crazy hot summer days and have someone put in a small split system strategically located in 2-rooms to save electricity costs and keep the house humidity under control when it's below 90-deg outside.

That's probably way to much, but also consider a couple of window units for those cooler shoulder months to keep the temp and humidity under control.

Diggity said:

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I don't know that the blower in the attic is variable speed.

You may have exceeded my limited knowledge of HVAC.

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Have him send you (so you can post it) the make & model numbers of the HVAC equipment from his inspection report

good call. I'll do that

YORK TG8S TECHNICAL MANUAL Pdf Download | ManualsLib

Says it has a 4 speed motor.

Could possibly slow it down to provide more humidity removal if it will still operate without freezing up.

I'll defer to someone more familiar with York equipment, but it looks like there are 4 speed setting on this blower (see page 24 linked below). It does not appear to have variable speed or ramping capability (diagram from my previous post). However, by lowering the blower speed setting, you increase run time and more effectively dehumidify the air. He or his HVAC guy may be able to set the blower on a lower speed setting than where it currently is to increase comfort.

https://www.theacoutlet.com/documents/Installation-Guide-York-TG8S.pdf

ETA- TexAg1987 beat me to it

am I crazy, or did I share the part number for the furnace?

You did. The furnace also blows the air during the cooling cycle. Not just when heating.

well you see...I just learned something!

Yeah it's not intuitive that you'd use your furnace when its 100F outside

"tech is saying that the tonnage is way too large"
Well, for that era 4 tons might be apropos so if 20% larger is "way too" then agree
Smaller houses have lived with a 5 ton single stage before and survived it, the noise through ducts being the biggest problem
If humidity is a problem, they sell plug-in solutions for that.

Looking ahead, saving money for a replacement system when the 5 ton either a) gets at least 15yo or more, b) energy bills get high enough to justify would be ideal.

• the Manual J computer report (if input via someone savvy) will predict the best tonnage, etc.
• variable speed is the only way to go these days IMHO
• Consumer Reports has ratings on brands
• Pubic reviews may have ratings on the potential installers that can either make or break how a system works in real life

Pier and beam house or slab ?

How tall of ceilings ?

Single pane or wood windows ?

What is the attic insulation situation like ?


If it was me, i would get a humidity meter and see what levels he currently has.

If it is short cycling there a few things he can do to slow the air flow down to make it run longer and pull more humidity out. Cheapest is to run a high merv allergy filter that will slow airflow down on the coil. The hvac tech can also drop the blower speed down to do this as well.