[jaseinatl]

Sorry, that's a terrible title, but here is the question as best I can put it:


I live in an open loft area with a centralized heat pump. Often, I will find that though I have my thermostat on COOL, it is hotter inside than out. Often, when I have my thermostat on HEAT, it is colder inside than out.

It stands to reason that if I want to COOL the inside, the heat pump would have to do less work if it could choose the coolest source of incoming air (be it from outside or inside).

By that same logic, HEAT would simply pick the warmest source of air as it's starting point and apply heat.

Currently, all of the air is coming from inside and if it is hotter than outside, I have to cool all the air inside just to get relief. Sure, I could open a window, but I don't have any windows and no circulation for air.

I simply want a device that could act autonomously from the Heat Pump that sits directly in the air intake portion of the system.

When the heat pump starts in COOL mode, the first device (intake) would compare the temperature outside to the temperature inside and simple apply a mechanical switch to allow the coolest source to enter the heat pump.

When the heat pump starts in HEAT mode, the first device (intake) would compare temps and pick the hottest source.

Does this kind of thing exist? If not, let's build one and win a Nobel prize for the amount of energy we could save.

Any information would be greatly appreciated.

 

[jaseinatl]

In fact, I am actually going to try this and report back. I can mount an air intake with a seal that allows air to come in from the outside. Then, I'll take my normal air intake tube and place a Y in it with a simple paddle that I can rotate to allow one source or the other. If it's cooler outside and I want to cool off, I'll flip the switch which allows the cold outside air to come in. I'll report back with my results.

 

[beenthere]

Already exist in commercial systems, for the cooling side. Its called an economizer. There are some versions of it or residential also.

The problem you will run into, is that for it to work. You also need a way to exhaust/get rid of the inside air. You can't bring in outside air, if your not blowing the inside air out of the building also. So in order to bring in 600CFM, you need to be abl to exhaust 600CFM back to the outside.

 

[roughneck]

Youll need a way to exhaust air out of your house while your bringing in fresh air, as described above. You'll also need to monitor outdoor humidity to make sure you don't flood your house with moisture. Most commercial systems have ways of doing this.

 

[supers05]

We call this an economiser. The ideal setup is 2 linked mechanical dampers and a third (mechanical or gravity) damper allowing air to exhaust. You close the return source that you don't want and open the return source that you do. This is based on enthalpy sensor(s). (Ideally, differential enthalpy) Depending on the system, you'll need an exhaust fan to keep the balance as BT mentioned.

There are a variety of manufacturers that make a variety of variants. (Honeywell being one of the biggest in the industry for the controls. Honeywell and Belimo share the actuator side)

This will cover the basics and then some. https://customer.honeywell.com/resources/techlit/TechLitDocuments/63-0000s/63-8594.pdf

http://blog.micrometl.com/wp-content/uploads/2014/04/Power-Exhaust-Illustrated-At-MicroMetl.jpg

Cheers!

 

[jaseinatl]

Thank you to everyone who replied. I am checking out a couple of residential economizer's now. I appreciate the info. If anyone has any experience with a residential economizer and has a reference or suggestion, I'm all ears.