Please Help Me Solve This Puzzle

[AKGreen]

I am attempting to plumb my Central Boiler OWB. The attached pdf. is what I came up with. Will this work? Ultimately I would like to be able to turn the thermostat down on the HWH so that it only comes on if the OWB goes out.
Any Help would be greatly appreciated.

 

[arbutus]

I am attempting to plumb my Central Boiler OWB. The attached pdf. is what I came up with. Will this work? Ultimately I would like to be able to turn the thermostat down on the HWH so that it only comes on if the OWB goes out.
Any Help would be greatly appreciated.

I'm a hydronic newbie, but why do you actually need two pumps on the owb line to overcome head? I think I have read here that if you do they should be coupled together.

 

[AKGreen]

Thanks for the reply Arbutus. I have two pumps for the sake of redundancy. Is their a better way to install the second pump? I live in a part of Alaska that in the middle of the winter if a pump goes out you dont want to be spending a lot of time replacing it. If I can get away with it I wouldnt have power to the second pump until it was needed. Now that I am looking at it a simple bypass would solve all of my issues allowing me to isolate the pump that needs repair, while allowing the system to continue. Thanks for excellent observation.

 

[Bob Rohr]

Thanks for the reply Arbutus. I have two pumps for the sake of redundancy. Is their a better way to install the second pump? I live in a part of Alaska that in the middle of the winter if a pump goes out you dont want to be spending a lot of time replacing it. If I can get away with it I wouldnt have power to the second pump until it was needed. Now that I am looking at it a simple bypass would solve all of my issues allowing me to isolate the pump that needs repair, while allowing the system to continue. Thanks for excellent observation.

Pumps fail in the motor 95% of the time. Or in OWF they cavitate to death, If you keep a spare in your home or shop, as long as you have isolation valves on both sides of the pump, a motor can be changed in a few minutes with a long allen wrench. Really no need to pipe them both in place.

Buy the spare pump and tape the correct allen wrench to the side of it fo if an when you need it.

It's not uncommon for pumps on OWF to fail. Often they are mis-applied ( pump is oversized for the piping it is connected to, or operating without sufficient NPSH) if they fail in less then 20 years