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second circulator on L8148E?

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steamedchicago
steamedchicago Member Posts: 72
in Radiant Heating
I have a Peerless conventional hot water boiler, attached to what was originally a gravity system. There are two branches, one for the front of the house, the other for the back. The cast iron radiator in the back bedroom was replaced with a Myson T6 panel. The 1 1/4 iron pipe that fed it was dissassembled, and necked down to 3/4 copper. It runs about five feet, and then tees. One tee, in 3/4, feeds a radiator in the basement, right under the supply. The other is 1/2 copper, and runs ~10 feet along the wall before going to the Myson upstairs. The Myson does not get hot in normal operation. (It did yesterday, when the boiler ran for four hours after being drained to replace the expansion tank, which started leaking on Christmas. TRV on it even cut it off, on the highest setting. So it works if it gets hot water.) The cast iron radiator in the basement does get hot.

I think this means we need to add a small circulator for the panel rad. Where the iron pipe transitions to copper would be the easiest spot. The question is, can I do that? The boiler has a Honeywell L8148E. I am not sure of the subtype, one that runs a motorized damper. There's a Bell & Gosset NRF-22 at the boiler (pumping through the boiler, sigh). Can I drive a relay, located at the pump, from the L8148 using a low voltage signal? It's about 30 feet, as the pipes run.

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  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
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    Do you want both circulators to run at the same time?
    steve
    steamedchicago
  • steamedchicago
    steamedchicago Member Posts: 72
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    STEVEusaPA said:

    Do you want both circulators to run at the same time?

    Yes, I have no way to zone anything, so the second circulator would be a booster.
  • Jamie Hall
    Jamie Hall Member Posts: 23,284
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    Having altered the hydraulics of your system so drastically, there isn't much else you can do than add a small circulator in there. Even so, you are going to have an interesting time balancing things out -- you will need to put some balancing valves in there too.

    That said, is there any good reason why you can't wire the small circulator in parallel with the boiler pump? No need for a relay, if they aren't going to be controlled separately.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • steamedchicago
    steamedchicago Member Posts: 72
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    Jamie Hall said:

    Having altered the hydraulics of your system so drastically, there isn't much else you can do than add a small circulator in there. Even so, you are going to have an interesting time balancing things out -- you will need to put some balancing valves in there too.

    That said, is there any good reason why you can't wire the small circulator in parallel with the boiler pump? No need for a relay, if they aren't going to be controlled separately.

    There are plenty of valves available, at least on the new pipe. I like to be able to isolate as much as possible.

    If I can use a low voltage controller, I can run the wires along the pipe. If I hook it up using the aquastat's pump output, I have to run conduit. (I have to run some anyway, but much less). I also wasn't sure if I could do that, but I see the L8148E can run 7.7 A circulators, which is much less than my two pumps will draw.
  • ricka1234
    ricka1234 Member Posts: 5
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    You could try using a monoflow tee, to try2force water up in2the 1/2 branch.. as commented already, system piping has been modified from original piping.. also, maybe try either slowing down velocity of water traveling thru system. If current circ doesnt hav speed options, maybe replace & put on slowest speed.. with dif sized piping everywhere, slowing water down will allow it 2 flow in2smaller branches. Good luck
  • steamedchicago
    steamedchicago Member Posts: 72
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    I installed a Grundfos UPS15-58FC this afternoon. It's wired in parallel with the main circulator. Would have been hour job, if the installer who wired the boiler wasn't an idiot. Had to redo all the boiler supply conduit and wiring, so it took 3.5 hours. I've only had a couple cycles since the pump has been installed, but the panel gets hot as soon as the water leaving the boiler is hot. I'll worry about balance over the next couple of days (supposed to be a high of 5 tomorrow, I should have plenty of chances).

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