probably dumb, had to ask

[Rick Stanley]

There have been posts here about keeping supply pumps down low on a Garn system to prevent suction boiling. The idea is to keep the pump as far below the water level of the tank as possible.

I've started to put the near-garn piping in place, with pumps right on the floor. Since my manifolds, pumps, etc are all behind the boiler along with the horizontal flue and combustion air intake pipe it's gonna get crowded in there and would make better use of the space I have and make it easier to get in there for maintenence and repairs, if the return manifold and return lines were high enough to walk under them. By putting them up there out of the way, they are quite a bit higher than the water level in the boiler. Is that gonna cause any problems?

Thanks

 

[WoodNotOil]

I assume that your supply and return are on the pressurized side of the plate heat exchanger since the Garn is unpressurized, right? In that case, put them anywhere you want. The below the water line probably only applies to your pumps on the Garn side of the hx. Just a guess though...

 

[Rick Stanley]

Nope. I'm talking about the Garn (unpressurized) side of the hx.

 

[WoodNotOil]

Hopefully someone else will chime in, as I am not a Garn owner. In my experience you want everything well below the water line otherwise keeping it primed, etc is a pain. This way the weight of the water via gravity helps the flow a bit, I think...

I always assumed the water from the Garn went through one or perhaps a couple of heat exchangers and then distribution happened on the pressurized side of the hx. How many pumps and distributions are you putting on the unpressurized side and where are they going? Just curios, because I don't know a ton of how Garns are hooked up.

 

[Rick Stanley]

You are right. The distribution for my house will happen on the pressurized side of a heat exchanger near my oil boiler in my basment. The garn is 170 feet away from the house in another building (ditch work is done) and the distribution manifolds (that I'm asking about) near the garn will be to heat three other buildings(zones) besides the house. So all of the piping near the garn is gonna be unpressurized. At least that is the plan at the moment..................

So, you think it may well be a problem having the return header higher than the water level. Guess if all of the pumps were off, prime would be lost?? Is that the fear?

I can put it down lower, I just thought it would be good to get it up there out of the way. Lot's to consider............................

 

[WoodNotOil]

Yes, I would suggest putting it all lower.

 

[Jim K in PA]

Rick - are you using the lower bung for the return and the upper bung for the supply per the current GARN manual?

Are you running P/S? (sorry if you already told me this in another thread).

If you do put a portion of the return loop up above static water level in the GARN, I would make sure to put in a way to bleed air from the highest point.

 

[Rick Stanley]

Yes, lower bung is the return and upper is supply. Not p/s.

It was just a thought I had to put it up overhead. Turns out, not a good idea. I can put it low on an adjacent wall. It can be a couple of feet off of the floor with no problem, right?