Dual Boiler Hookup: Controls

That would be the other book," Electrical wiring of boilers" . Standard edition # 29. Scott

I have the SP-83 along with the digit-stat DS-60, D-135 and like them.

beatle78 wrote:Sting,

What books out of the ones I ordered talk about using those relays for controls? I didn't see anything in "Pumping Away". These books seem to focus more on the plumbing side of the system.

Thanks,
Jeremy

Using Fan Relays is something I learned from a dead plumber - Ice cube relay intimacy came more recently!

Nice belt buckle.

stokerscot wrote:That would be the other book," Electrical wiring of boilers" . Standard edition # 29. Scott

That didn't come with my series!

Sting,
Beetle'78,
Haven't seen the obvious, huh?
the use of a zone controller negates the low limit on either your coal boiler or your oil boiler if you're using an 8124. Six zones, six relays. Use double pole relays. One set of normally open contacts run in parallel to close the t-t contact on your boiler controller. the other set individually control the circ pumps with their associated t-stats. The power that is switched by the second set of contacts originates from the c1-c2 points on the 8124. That way, the low limit is useable and your boiler comes up to temp before allowing the zones to operate. This is if small low wattage pumps are used. If large high amperage pumps are used, then your controller won't support the combined load of six large pumps. I hope this was all spelled correctly Scott

HUH???? Wasn't I clear AGAIN!!!!!

well here goes it.my system consists of a weil-mclain cg-5 gas boiler and a keystoker kb-8 coal boiler . the gas boiler came with 1 relay with 2 sets of terminals, the coal boiler came with a honeywell 8124 a , I think, ialso have a argo 6 zone relay box. here goes the wiring. the thermostats are connected to the argo unit, the argo controlls the gas boiler, the relay in the gas boiler has 2 functions,turn on the gas and call the coal boiler, heres how. the relay has 2 sets of contacts, set 1 calls the gas, through a imc 102 timer relay, (grainger # 4e223, $12.95) to delay the gas valve up to 15 min. and a factory installed aquastat to controll the water temp, which is set approx. 10 deg. lower than the coal .i have a rib relay hooked in parelell with the gas valve, i'll explain this next. the 2nd set of contacts was for the pump, but I disconected the ac connections, I use this pair to call the coal boiler, but I used the rib to break the call for heat if the gas valve opens, allowing the gas only to heat the house, if not , the pump on the coal boiler would continue to run and use the heat from the gas to be wasted up the chimney of the coal boiler. the coal boiler is hooked up as described in the installation manual. hope this helps, with some simple modifications this could be used for oil/coal install

TGMC,

I like that timer relay!

OK let me see if I have this straight.

When you get a call for heat from the zone controller, it goes to the Gas boiler. The C1/C2 on the gas boiler is hooked up to the ZR/ZC on the coal boiler's L8124A(instead of a circulator). The Line Voltage to the gas valve is sent to a timer relay. At this point the water from the coal boiler is circulating through the gas boiler. As long as the water from the coal boiler keeps the water in the gas boiler above it's set high limit, the delay relay never activates the gas burner.

My boilers are basically in parallel so there is no water running between the 2.
I could do something similar except I will use the coal boiler as the primary. I can use an aquastat on the supply of the coal boiler to intercept the Line Voltage to the burner on the oil boiler. If the coal fire goes out, the burner on the oil boiler will fire. If the coal fire stays hot, the oil boiler will never kick on.

So I have 2 options.

1. Do what I described above
2. Do as Sting suggested and just leave 1 extra T-stat in the house hooked up to coal boiler. If the house gets cold, the oil will fire. The only issue Sting's method doesn't solve here is summertime use for domestic hot water, but I plan on running the coal boiler year around.
Thanks!

TGMC, Beatle78, You guys probly have this covered, but where is the power for the stoker timer originating? Scott

the coal boiler is set to stand alone.

the c1/c2 on the gas boiler calls the t t on the coal boiler. the gas valve is 24 volt. if you use 2 honeywell 8124a controllsuse 1 more cube relay on the c1/c2 output of the oil boiler.the oil boiler is actually called first but is the secondary boiler in this configuration.

That way looks like it will work pretty good with your boilers hooked in series. That situation won't work with a parallel or pri.-sec. loop. Scott

stokerscot wrote:TGMC, Beatle78, You guys probly have this covered, but where is the power for the stoker timer originating? Scott

scot,

excellent question! The power to the timer is coming form the L1/L2 on the 8124.

hey Sting,

Check out toe TACO zone controller.

http://www.designheating.com/Catalog/Product_deta ... tID=288602

It uses the ice-cube relay's and they are REPLACEABLE! All in 1 little nice package! Sweet huh?

EDIT:
And this one will interface with an outdoor reset....
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