why 2 seperate water systems for heat storage?

[fabguy01]

hi, i am in the prosses of planning my boiler system and was wondering what are the advantages of using a hot water coil to heat the storage? I would think that it would be eiser,cheaper, and more efficiant to use the same water troughout. Thanks nate

 

[Nofossil]

This is basically the pressurized vs. non-pressurized debate. You can find plenty of threads that talk about it. Short answer - pressurized needs no hx, is higher performance, maybe more expensive, can't easily have extra hx for hot water preheat or solar panel input.

 

[fabguy01]

So, from what i've found the coils inside the tank is for running press boiler with non-press storage? What about non press boiler with non press storage tank? I am building my own boiler and the storage will be 2-500 gal LP tanks. From what iI gather it would be the same as a OWB water system. Anyone have any thoughts? Thanks Nate

 

[sdrobertson]

So, from what i've found the coils inside the tank is for running press boiler with non-press storage? What about non press boiler with non press storage tank? I am building my own boiler and the storage will be 2-500 gal LP tanks. From what iI gather it would be the same as a OWB water system. Anyone have any thoughts? Thanks Nate

If the heating zone will be through a forced air furnace then you can hook it up like a OWB. If its water heat (radiant or baseboards) then you will need the heat exchanger. The advantage I see for pressurizing the storage and lines to the house would be allot less chemicals to prevent rust. This would require use of a heat exchanger from the boiler to the tanks. If you ran everything unpressurized then everything could be hooked together and just figure out how you want to treat all that water. I think the costs would probably balance each other out at first as the cost of the chemicals and the cost of a large enough heat exchanger should be close. In the long term, the chemicals would cost allittle more. The other problem I see with it all being open, you will have to figure how you want to keep all the vents at the same level - as the water will try and find the easiest way out and if the boiler or tanks are lower, it will flow out until their level.

 

[Nofossil]

If your boiler and storage are unpressurized, then you'll need a heat exchanger between storage and your house assuming the heating system in the house is pressurized. The only way to get around the need for a heat exchanger is for everything to be pressurized (or unpressurized, I suppose, but that's almost never done).

 

[sdrobertson]

If your boiler and storage are unpressurized, then you'll need a heat exchanger between storage and your house assuming the heating system in the house is pressurized. The only way to get around the need for a heat exchanger is for everything to be pressurized (or unpressurized, I suppose, but that's almost never done).

Most of the OWB boiler installs around here are used as unpressurized as the boiler runs water directly from the boiler to the air handler installed in the furnace. This was how mine was plumbed originally until I switched boilers and went to pressurized. My mistake was using non-O2 barrier pex for the underground and in-house lines to the air handler. I'm planning on switching these this summer so I would suggest that everyone install O2 barrier pex as you never know when you may need it.

 

[fabguy01]

Thanks for the info guys, I am quite familiar with the traditional OWB systems but have 0 experience with a the new stuff coming out. The reason for my post ,and I am now pretty much set on is that my current OWB setup holds all the storage 100' away from the house to a heat exchanger in the furnace, And providing the guy down the road comes through and buys my current boiler my next system will be a MUCH refined boiler with minimum water around firebox/heat-extractor and hold most of the water under the house.press or not is still to be determined

 

[sdrobertson]

Thanks for the info guys, I am quite familiar with the traditional OWB systems but have 0 experience with a the new stuff coming out. The reason for my post ,and I am now pretty much set on is that my current OWB setup holds all the storage 100' away from the house to a heat exchanger in the furnace, And providing the guy down the road comes through and buys my current boiler my next system will be a MUCH refined boiler with minimum water around firebox/heat-extractor and hold most of the water under the house.press or not is still to be determined

I went with pressurized as that was what was locally easiest to come up with and I personally like not using another heat exchanger.

 

[fabguy01]

So, I've done a little more reserch and am starting to lean torwards pressurized, a few mor questions :cheese: how much pressure do these systems typicly run?will my current barrier pex hold up? because Im really not in the mood for another hand dug trench.and do I have to get different style pex fittings? I currently am running the compression style with the plastic collet
Thanks again for all the help Nate

 

[Piker]

15 psi norm... 30 psi relief. If you have barrier pex, it should be fine.

It never hurts to use the best fittings you can find. I would steer away from plastic. I have seen a couple guys who have used the sharkbite fittings on their pex. No problems so far. I don't know if I trust them enought yet to put in locations where you can't easily access them (though they are ok for that), but if someone wants to use them out in the open I definitely don't see a problem.

There are alot of plumbing contractors who refuse to use them. I am not sure whey. Probably because they seem too good to be true.

cheers