Hydronic Heating in our farm greenhouse

Farmer Ron -------------------------------------
Okay, this is a weird one, but... we're farmers, so everything here is weird. Maybe someone here will be inspired by our "challenge" and help us out!
I have a very "home built" hydronic heating system in our 1500 sq ft farm greenhouse. It's awesome... we save hundreds of dollars each spring in propane because we just heat the benches instead of the air. The plants grow faster too with warm roots.
It's a is that it's a leaky system, which I don't mind... mice nibble at things, etc. we're always adding in 2-3 gallons of fresh water each day, but who cares, we're in a greenhouse with dirt floors... The PROBLEM is that there seems to always be "new air" coming into the system and when it gets into our "boiler" it stops working.
I have two air vents in the system one before and one after the boiler. I have two taco 007 circulator pumps moving the water around. Our "boiler" is an Bosch Aquaster instant on hot water heater that kicks on when 1/2 gallon a minute of water is flowing through it. Please note we've been using this system for 7 years as is now... so it works... it's just that I have to keep manually "purging" the system by opening strategically placed faucets to get the air out, and sometimes, if it runs a lot at night, it shuts down unless I wake up at 3AM to re-purge it. The money we save actually makes it worth it, but I'm getting old and it's cold and I just wish it would work.
Our boiler is basically at the same level as out benches. The top of it is a couple feet higher, actually. Could that be why the air gets stuck in there instead of purging out the air purge things? I have tried replacing the air purge vents, but that does nothing for me.
Does anyone have any thoughts about this?
THANK YOU! Ron
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Farmer Ron -------------------------------------
Okay, this is a weird one, but... we're farmers, so everything here is weird. Maybe someone here will be inspired by our "challenge" and help us out!
I have a very "home built" hydronic heating system in our 1500 sq ft farm greenhouse. It's awesome... we save hundreds of dollars each spring in propane because we just heat the benches instead of the air. The plants grow faster too with warm roots.
It's a is that it's a leaky system, which I don't mind... mice nibble at things, etc. we're always adding in 2-3 gallons of fresh water each day, but who cares, we're in a greenhouse with dirt floors... The PROBLEM is that there seems to always be "new air" coming into the system and when it gets into our "boiler" it stops working.
I have two air vents in the system one before and one after the boiler. I have two taco 007 circulator pumps moving the water around. Our "boiler" is an Bosch Aquaster instant on hot water heater that kicks on when 1/2 gallon a minute of water is flowing through it. Please note we've been using this system for 7 years as is now... so it works... it's just that I have to keep manually "purging" the system by opening strategically placed faucets to get the air out, and sometimes, if it runs a lot at night, it shuts down unless I wake up at 3AM to re-purge it. The money we save actually makes it worth it, but I'm getting old and it's cold and I just wish it would work.
Our boiler is basically at the same level as out benches. The top of it is a couple feet higher, actually. Could that be why the air gets stuck in there instead of purging out the air purge things? I have tried replacing the air purge vents, but that does nothing for me.
Does anyone have any thoughts about this?
THANK YOU! Ron
##-----------------------------------------------## Delivered via http://www.www.thestuccocompany.com/ Building Construction and Maintenance Forum Web and RSS access to your favorite newsgroup - alt.hvac - 25694 messages and counting! ##-----------------------------------------------##
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If you have even a small amount of leakage then that would be the cause of new air in the system. You need to repair the leaks. Whenever the system idles without the heat on it cools and there is a negative pressure which sucks a bit of air in.
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Do you have a fill valve, that's set to a certain pressure?
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