# 100 gal nat gas heater tied to rooftop cooling unit



## Nathan901 (Feb 11, 2012)

So I was trying to make sense of a system in a commercial building. Im thinking how it is configured at the heater is incorrect, and was wondering if anyone here might be able to make sense of my rambling.

What I have is a 270,000 btu 100 gal nat gas heater.

Stubbed out of the wall there is a total of 5 pipes.
Four 1 1/2 pipes and one 1 inch pipe for the recirc.

The other two pipes that aren't hot or cold go up and out through the roof in 1 1/2 inch copper to a big cooling system that is inside an aluminum box about the size of a mobile home. Inside there, they tie into a little tank in the corner.

The tank has two 3/4 inch side inlets that the water lines tie into, and two larger copper pipes on top that connect into the other piping. The weird thing is the two larger pipes that come out of the top of the heater(also 1 1/2 inch copper) are labeled "to heater" and "from heater". That's the first thing that threw me off. They appeared like they possibly might not have been factory lables though.

So I assume the tank would just the heat of the cooling system to help heat the water? Nowhere on that stretch of pipe from the heater to the cooling area on the roof was there a pump for those lines.
Its also a pretty far run to the roof, id say about 100 feet there and 100 feet back.




My question is..... What is the proper way to incorporate it into the heater piping?


I was told to tie it together with the recirc and a balancing valve? And connect the line that feeds the tank on the roof into the cold? 

Did any of that make sense?


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## rjbphd (Feb 5, 2010)

Nathan901 said:


> So I was trying to make sense of a system in a commercial building. Im thinking how it is configured at the heater is incorrect, and was wondering if anyone here might be able to make sense of my rambling.
> 
> What I have is a 270,000 btu 100 gal nat gas heater.
> 
> ...


To/From heater are usually for connection on space heater coil...


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## Burner tech (Oct 24, 2013)

Im having a hard time picturing this exactly (sorry im a very visual person) but, if you have a loop off your heater, you need something to move that water. So yes you need a pump. 

Either they are trying to move water from the heater to this tank(most likely has a heat exchanger in it) to pull heat from the system, or to give heat. Regardless with out being able to move the water how are you continuing to transfer heat.


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## Nathan901 (Feb 11, 2012)

Yea I'm almost positive that a pump is missing from the system. I know it's not crucial to the cooling system as there are three other rooftop system setups without connections to a heater. 


How much energy could this setup possibly save? Natural gas is cheap, and it's a Wally World so how much hot water would you even think they use? 


The only way that this system could make sense to me is if the tank on the roof would feed the heater warm water.

The whole thing just doesn't compute with me unless the tank had 1 1/2 ports. I'll have to take some pictures


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## Fred Meebley (Jan 26, 2013)

the heat from a large refrigeration unit being reclaimed with a water cooled condenser is free heat that would just be exhausted into the atmosphere and is a significant amount. It is also critical for that refrigeration unit. At the Walmart that I service, the circ. pump and piping is my responsibility, but the tank is only serviced by the refrigeration company. If you are dealing with a shortage of hot water, find the circ. pump and check the coupling between the motor and pump. My Walmart has the pump mounted in the refrigeration rack house. There should also be a massive set of drawings somewhere in the back of the store that you can reference. Good luck, and I wouldn't recommend replumbing anything without talking to their refrigeration contractor.


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## Nathan901 (Feb 11, 2012)

Thanks for the input. But the job has been completed. 
We piped it all back in just to find out there was actually a automatic valve on the roof that controlled when it would allow water to flow through the cooling unit and it was not functional. We told them about the issue and said they were about to do a complete overhaul on the cooling system so we isolated it until that happens.


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