DIYer with another question

Pete_31

HTP told me today that MC-50 has about 6 amps available, the boiler only uses 1.6 of that. So they saw no problem with me starting 2 pumps off of their P1 terminals. I'll finish wiring tonight and add glycol tomorrow. Hopefully, borrow an analyzer from one of our service fitters later this week. I have a feeling, as you guys probably know, that you'll see more questions from on this. Thanks again to everyone who has responded to my queries.

Pete_31

Control question

I think I'm almost done with my Munchkin MC-50 installation in my workshop. Thanks again for the answers to my buffer tank and glycol questions. OK, I see on the boiler's terminal strips where to connect the O.A. sensor, power, primary pump and t-stat. I'm unsure of how my systems single zone pump is controlled. Do I need some sort of relay. The install manual shows several scenarios but not my 1 zone, no control valve, no DHW situation. I asked an electrician at work, he thought I needed something called a RIB relay, any help would be greatly appreciated, it's getting chilly here in Minnesota.

hot_rod

I wonder

that both the primary and system pump could be wired together. If the relay is adequate to handle two circs of 80W or so. I can't find any info to tell how much that internal relay could carry.

A separate relay could easily do the trick. Taco, Honeywell make 'em. B&G and a few others have relays that fasten right onto the circ electrical connection box.

hot rod

tim smith

Safe and easy answer for weekend

Hard wire system pump to power supply and get some heat! Call Heat Transfer tommorow and make sure relay can handle both pumps which I am sure they can but just to be safe for warranty purpose etc. If you are using 2 UPS1558 or equiv Tacos, the load is only 1 - 1.5 amps max and relay I'm sure can handle that. Tim

Pete_31

I see that there is a spot on the terminal strip for a DHW pump. Does that mean that the boiler is capable of powering 2 pumps at the same time? With no buffer tank in the system, would there ever be time when both pumps wouldn't run simultaneously? Primary pump 92w, secondary 85w.

hot_rod

constant circ!

Tim has a good idea. Let the system pump run 24/7. The wall stat fires the boiler and primary loop pump. With a vision 1 control. which I believe all the new ones Munchkins ship with, you get outdoor reset ability.

With some experimenting you should be able to dial in a reset curve to provide a very comfortable control system.

hot rod

tim smith

You can't use that for heating

Pete_31

I didn't think I could. I was thinking that it might mean the boiler had the capacity to run 2 pumps at the same time. So if I'm understanding you guys, secondary pump is only controlled by me throwing a toggle switch at the beginning of the heating season. Everything else is taken care by the boiler right?

tim smith

Noooooooo

I am suggesting just hard wire for temporary then if the contacts on relay can handle both pumps, put it on with boiler pump then. What Hot rod is saying is run constant circ always which could be good benefit, If that were the case, maybe tie it into an outdoor thermostat set at 65 or so to shut it off in non heating weather or use 2 stage stat and wire it into relay so first stage would be constant pump and 2nd stage boiler. You would set this up maybe 2 degrees higher that desired room temp so 2nd stage would be the actual room temp.

Pete_31

Ok, if HTP says its alright, land secondary pump on the same terminals as primary pump. No relays or anything else needed?I like the simplicity of that. As you guys can probably tell, simple is what I need.