Sizing heat Pump and Zone or not

[go_redskins]

Originally posted by jtalbert
To Review: HVAC-CALC 4.0 gives me:
Sensible Gain 20705
Latent Gain: 1954
Total Heat Gain: 22659
Total Heat Loss: 38163
Calc program Recommends a 2 ton system
Heat pump to be installed for AC and heat

Just talked to one of the HVAC contractors I have asked for bids and he said that the TVA here in Tennesee recommends to size system up to 125% of the sensible heat gain. That is to keep the heating element from coming on too early in the heating mode (aprox 35 dgrees) and degrading efficiancy.

Does anyone know of this recommendation? I have not read anything on the forum regarding upsizing the system tonnage according to heat losses. I would appreciate any clarification on this issue. Thank you

Question for all.

A 2-ton AC or HP may have 24000 BTUH total cooling capacity. But the sensible cooling capacity is only about 18000 BTUH. So should the system be sized using total cooling capacity or sensible cooling capacity?

[beenthere]

Higher HSPF, units, usually have higher btu output at lower temps.

Which in turn prolongs the strips from coming on.

[beenthere]

Actually it should be sized to bothe, the sensible and the latent.

Thats what manual S is for.

The indoor and outdoor unit are to be matched to handle both loads.

[go_redskins]

Originally posted by beenthere
Actually it should be sized to bothe, the sensible and the latent.

Thats what manual S is for.

The indoor and outdoor unit are to be matched to handle both loads.

That would mean a 2-ton is too small for his sensible gain of 20705 especially since a lot of 2-ton's have sensible cooling capacity less than 17000.

[beenthere]

You'll find that you get some of the latent ability to become sensible after the humidity is down, it might not be enough for your house. And duct system.

Your contractor will have to check teh spec sheets for the equipment he handles to select the correct match up, and yes 2 ton could fall short on sensible, depending what you keep your stat set to,

that is also in the manual S.

[dan sw fl]

[QUOTE]Originally posted by go_redskins
[B]

Originally posted by jtalbert
A 2-ton AC or HP may have 24000 BTUH total cooling capacity. But the sensible cooling capacity is only about 18000 BTUH.

So should the system be sized using total cooling capacity or sensible cooling capacity?

Just be SENSIBLE about it everytime.