I have central boiler stove which is running hot water using 1' 1/4'' pex to 30 plate heat exchanger. The stove is 100 feet away and has a taco 0014 pump on it. The inside boiler that has connection to heat exchanger is using 3/4 inch pipe and a taco 009 pump. The outside boiler reades 185 degree's and the inside boiler shows 130 degree. Local plumber is saying that the 3/4 inch pump needs to be increased to at least 1 inch copper with a 0014 pump to push more of the inside water through the heat exchanger. Anyone know if this sounds right or could it be the heat exchanger plugged or undersized?
Heat not getting transferred to existing boiler
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Eric Johnson
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I don't think you need a bigger pump. I had a similar arrangement once, and I used 3/4-inch copper and a Taco 007 to move water through the hx. The thing I noticed was that it took quite awhile to get the heat into my gas boiler. It didn't seem like a very efficient arrangement to me.
Where is the water from the hx going into the existing boiler? The top or the bottom? If you run it into the top, you'll get the heat into your house faster, since the hottest water is what goes up into the zones. If it's pumped into the bottom, then it has to heat up all that water above it before you see any benefit. Also, is your flat place piped to counterflow? The water should be moving in opposite directions inside the hx for maximum efficiency.
If you think it's the pump, why not get one of those Grundfos 3-speed circulators? That way you can play around with the speed settings to see if it makes any difference.
Anyway, after my experience with the flat plate (which worked OK, but took a long time to heat everything up), I piped my new boiler directly into the house system. That got rid of the hx, the glycol and all the grief associated with that stuff. All you really need to do to avoid freezeups is to figure out a way to circulate warm water from your backup boiler into the wood boiler to keep it from freezing. Of course, in the event of an extended power outage, you'd probably have to drain the OWB side, but without anitfreeze, that's no big deal.
Where is the water from the hx going into the existing boiler? The top or the bottom? If you run it into the top, you'll get the heat into your house faster, since the hottest water is what goes up into the zones. If it's pumped into the bottom, then it has to heat up all that water above it before you see any benefit. Also, is your flat place piped to counterflow? The water should be moving in opposite directions inside the hx for maximum efficiency.
If you think it's the pump, why not get one of those Grundfos 3-speed circulators? That way you can play around with the speed settings to see if it makes any difference.
Anyway, after my experience with the flat plate (which worked OK, but took a long time to heat everything up), I piped my new boiler directly into the house system. That got rid of the hx, the glycol and all the grief associated with that stuff. All you really need to do to avoid freezeups is to figure out a way to circulate warm water from your backup boiler into the wood boiler to keep it from freezing. Of course, in the event of an extended power outage, you'd probably have to drain the OWB side, but without anitfreeze, that's no big deal.
Thanks for the response. The counterflow is set up correctly. The 3/4 inch copper goes to the bottom of the boiler. The plumber thinks that the hx is fine but that with the size of my system ( 3 zones, 3800 sq ft) i dont have enough of the indoor boiler water circulating through. 8gpm with a 3/4 inch he is saying is not enough to transfer the heat and that is why the indoor boiler shows 130 verus the 185 that is coming in from the owb. just worried that i am going to make the change and it wont help. CB said maybe the hx was undersized and i should go to a 50 plate verus the 30 plate.
Eric Johnson
Mod Emeritus
Ideally, you'd want to run your 1.25-inch piping directly into the backup boiler, as I described.
The plumber may be right. Somebody who knows the math could probably calculate your needs pretty accurately, but 3/4-inch pipe does seem a tad small for your setup.
And, as I mentioned, changing the input to the top of the other boiler might help and probably wouldn't cost very much to try.
The plumber may be right. Somebody who knows the math could probably calculate your needs pretty accurately, but 3/4-inch pipe does seem a tad small for your setup.
And, as I mentioned, changing the input to the top of the other boiler might help and probably wouldn't cost very much to try.
Dave T
New Member
Yeah trust your plumber's word on this one, bigger pipe moves more BTU and 3,000 sqft is too much to heat with 3/4 to all zones..Dave
91220da
Member
Just something to check. My existing boiler temp gauges were corroded and giving me false readings. My oil furnace temp gauge showed 130-140 but when checked with an IR thermometer it showed 165. I want to replace the boiler temp gauge but not interested in draining the system again now that it is up and running fine. Bought some clamp on thermometers and the temp numbers are fine.
Plumber changed out the pipes from 3/4 inch to 1 1/4 inch with 014 taco. he also put a temp gauge on inbound from HX to boiler and temp gauge back to HX from boiler. I a now showing 170 degree reading on my inbound and 165 on my outbound. 20 degree difference from OWB.
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