a question about make up air unit

[lemonmugua]

I have a project, there are 2 hoods exhaust around 3000 cfm air and I have to bring heated fresh air. but the gas landloard supplied is just enough for other service usage. I tried electrical heater. but that heater must to have around 75 KW power. that is a very big unit. What should I do in this situation?

 

[AbbyNormal]

does not sound like you need that much gas if 75 kW electric would work.

what will the landlord supply handle at 14 inches?

maybe talk to someone up on gas regualtores and see if you could run a 2 psi system.

The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install

 

[DrRTU]

Based upon your 75KW, you have an approximate 80 F degrees rise and only need about 250,000 btu/hr natural gas demand. Most meter and piping systems I see in the Midwest have ability to add this small addition and the field piping is the limiting factor. Did you look at an dedicated pipe run from the meter to MAU? The utilities we have worked with will swap the meter, regulator or spring assembly w/o charge if the load is going up. Cut down the exhaust flow, operate one One hood, utilize exhaust air energy recovery, use a percentage of room air as makeup or limit lower OA operation are the only ways to lower the energy demand of MAU system. Air to air heat exchangers are nice but the payback maybe long.

 

[engair]

RTU is right. A simple heat pipe system would work pretty well for you.

 

[xac33ncsu]

I'd caution about the use of heat pipe or anyother peak load shaving device. Whatever you will work nicely until your indoor temperatures get cooler than expected, suddenly you'll find yourself see-sawing to lower and lower indoor temperatures as your equipment can't keep up with the load due to the decreased performance of you're load shaving device (i.e. heat pipe).