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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22511
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This will be used for a stand alone fresh air system

Customer Question

This will be used for a stand alone fresh air system application. I was wondering which models can be used to run a fan only on a schedule and are capable of running up to 2 stages of electric heat to make sure output temperature is at least 55 when when exterior air temp is below that temp.
Submitted: 11 months ago.
Category: HVAC
Customer: replied 11 months ago.
Just wanted to clarify. Was looking for a thermostat that could easily handle this function. Will be running a Markel/TPI Hotpod as the heating and fan source. Have no particular brand preference for the thermostat.
Expert:  Phil replied 11 months ago.

Tell me a lot about the application and size of the building being served, and if you have natural gas in the area or not... electric make up air heat will cost a veritable fortune to operate in such a situation.

Thermostat is not a problem I will have to look up your model number on the Market'TPI hot pod though... do you have a model number on it?

We can go from there

Customer: replied 11 months ago.
Electric is the only source at the property. Model # HP8-1440120-2T
Customer: replied 11 months ago.
The engineer that sized the system is only calling for 150 cfm of makeup air. Application is retail commercial and store size is 1400 sf +/- well insulated with 11' ceilings.
Expert:  Phil replied 11 months ago.

That one will work great, it is 22 amp rated as well.

Its time to locate the 'finish and rate' link and click on it, that is the only way the company pays my time and expenses, in exchange I will hold the question open for any follow up you might need.

Customer: replied 11 months ago.
Sorry it will not. Need one capable of running fan only on a schedule and heat when needed using intake and outflow external temperature sensors.
Expert:  Phil replied 11 months ago.

OK thanks, ***** ***** few minutes I will be right back

Expert:  Phil replied 11 months ago.

I am unable to find a line voltage programmable thermostat with fan controls rated at the 22 amps you need to be reliable.

Expert:  BillyHvac replied 11 months ago.


My name is Billy. I am a bit confused by the design.

Why don't you just toggle the make up air to run when you heat and/or cool?

I have never seen make up air on a schedule other than occupied and unoccupied.

Plus the hot pods I have installed have a 24v control transformer built into the pod so the control is only 24v

Expert:  BillyHvac replied 11 months ago.
Customer: replied 11 months ago.
Main heating and cooling of the space will be from a ductless mini split. No way to easily link them together. If it was a duct-ed system, I would just run the outside air in to the return so that it could be tempered as needed. Because the make up air is separate system, I want it to program it to run the fan when the space is scheduled to be occupied and I do not want to heat the air unless the the intake air from outside is less than 55.
Expert:  BillyHvac replied 11 months ago.

I assume you are going with wall mount instead ceiling cassette with fresh air..

If you want to keep this simple and affordable...simply install a time clock (mechanical) like a paragon..or even a digital. Once store is open it gets power and when closes it disables. This could be done easily with the simple time clock.

The thermostat will not control a discharge temp as the unit would constantly go off and on (it is not a modulating make up system). So the best you can do is to have the thermostat in the pull side so that anytime the temp is below 50 being brought in the heat will function. Do you have plans when cooling as to pulling in 90 degree outdoor air?

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