Plumbing and Wiring Help Needed

Ash instead of Cash · Post by **Ash instead of Cash** » Fri. Oct. 03, 2008 5:10 pm

The new boiler is in at the dealer. I am going to pick it up tomorrow. Didn't think I was going to get it before the snow flew. Ordered it in June, asked about the lead time, guy said we aren't back at all on these, I'm expecting them in next week. Yeah RIGHT!!! At least I have it now.

Now for my dilema. The new boiler is going in the garage which is at the opposite end of the house from where the oil furnace is now. I am currently running 2 loops of 1 1/4" black iron pipe feeding cast iron radiators. I have tied in to the loop nearest the garage. See picture below. I feel I need to run both circulator pumps at once to distibute the water all through the house. Does this seem like a correct assumption? This is a hand fired furnace that is only going to run the circulator when the temp in the boiler reaches a set point. Also, how do I wire the circulator at the oil furace to still function if the coal fire goes out and the thermostat calls for heat?

I hope I am explaining myself well enough. Pardon the crude drawing. This is a great site. Thanks.

Jeff

BIG BEAM · Post by **BIG BEAM** » Fri. Oct. 03, 2008 8:15 pm

Is it a mono-flo system?Look at the tees where they feed and return to the radiators.If they have a tag on them that says Mono-Flow or Mono-Flo.These are usually on the returns in your cellar.
DON

Cap · Post by **Cap** » Fri. Oct. 03, 2008 10:46 pm

how do I wire the circulator at the oil furace to still function if the coal fire goes out and the thermostat calls for heat

Relay? Oil burner triggers coil in relay, sends 120vac to secondary circulator. This is how I'd be thinking.

Ash instead of Cash · Post by **Ash instead of Cash** » Sat. Oct. 04, 2008 5:03 am

Yes, it is a monoflow system. Also, I got a DHW coil in the new coal boiler. Should I put a bypass loop onthe coal boiler? Should the circulator pump be after the loop to try to keep more heat in the boiler for the DHW?

BIG BEAM · Post by **BIG BEAM** » Sat. Oct. 04, 2008 7:57 am

Is there a DHW coil in your old boiler?

Well to start with you're going to have to tie in the feed of the new boiler to the feed of the old boiler and the same with the returns.You just can't connect to the" loop" like in your pics.
The water in the system HAS to travel in the same direction as before.It seems like from your pics that you have a split loop mono-flo system.

The mono-flo tees have a restrictor in them and when installed on the return pipe from the radiators, thruogh veturi effect, suck the water back to the loop thus sucking hot water from the "loop" on the feed side.

I'll have to know a few more things like does the old boiler have a flow valve on the feed?

SMITTY · Post by **SMITTY** » Sat. Oct. 04, 2008 8:10 am

Cap wrote:
how do I wire the circulator at the oil furace to still function if the coal fire goes out and the thermostat calls for heat
Relay? Oil burner triggers coil in relay, sends 120vac to secondary circulator. This is how I'd be thinking.

Yeah -- maybe if you put one of those little thermostats (forgot what they're called) on the stove to trigger a relay, which would isolate the circulator from the oil furnace when the coal unit is hot, then when the coal unit cools down, it closes the relay & connects the circulator to the oil furnace again.

You'd need 2 relays -- one to connect/isolate the furnace & one to connect/isolate the coal unit.

Ash instead of Cash · Post by **Ash instead of Cash** » Sat. Oct. 04, 2008 8:15 am

Yes, there is a DHW coil in the oil boiler. As far as the flow valve, are you talking about a flow control valve to prevent themosiphon? If so, the oil boiler does have one of those on the feed side.

Isn't my water traveling in the same direction as before with the way I have it tied in? I don't have a good understanding of how this truly works. I just assumed if I pumped the water through the system in the same direction it is going now and ran the circulator at the oil boiler that it would push it through the entire system.

BIG BEAM · Post by **BIG BEAM** » Sat. Oct. 04, 2008 8:42 am

The water in the loop closest to the coal boiler is traveling in the same direction as before but not in the loop on the right side of your pic.If you hook it up like in your pics the water will go counter clockwise in the whole loop and as you can see in your pics the left loop goes counter clockwise and the right loop goes clockwise.

You will need to connect the feed from your coal boiler to the pipe between the flow valve on the old boiler and the tee where the mono-flo system splits

The return on the coal boiler has to be connected to the return on the old boiler between the circulator on the old boiler and the tee that brings the two loops together.
DON

BIG BEAM · Post by **BIG BEAM** » Sat. Oct. 04, 2008 8:51 am

Also no need for a bypass loop on your oil boiler(old boiler)
DON

One more thing.I would strongly suggest not to use ball valves in a mono-flo system,use full size gate valves.Ball valves restrict flow more than gate valves and the key to a mono-flo system is FLOW.

BIG BEAM · Post by **BIG BEAM** » Sat. Oct. 04, 2008 9:11 am

One more thing,try to run your feed and return lines from the coal boiler to the oil boiler as level as possible or at least with a
slight pitch up to the oil boiler.Mono-flo systems are very sensitive to air that gets locked in the system.
DON

Ash instead of Cash · Post by **Ash instead of Cash** » Sat. Oct. 04, 2008 9:22 am

The bypass loop already exists at the oil boiler. Do I need to eliminate it or put a shut off valve in it so when I am running on coal (as much as possible) I can keep the water from flowing through the bypass? Also do I need a bypass at the coal boiler to control my heat in the boiler for my DHW?

BIG BEAM · Post by **BIG BEAM** » Sat. Oct. 04, 2008 9:59 am

Is the bypass loop on the boiler because it's a fairly new replacement(does the piping on the bypass loop look newer that the rest of the system)?

I wouldn't put a bypass loop on the coal boiler,But some will debate me on that.
DON

Ash instead of Cash · Post by **Ash instead of Cash** » Sat. Oct. 04, 2008 10:06 am

Yes, I had a new oil boiler put in less than 10 years ago. Back in the days of 80 cent a gallon fuel.

Ash instead of Cash · Post by **Ash instead of Cash** » Sat. Oct. 04, 2008 10:15 am

Yeah -- maybe if you put one of those little thermostats (forgot what they're called) on the stove to trigger a relay, which would isolate the circulator from the oil furnace when the coal unit is hot, then when the coal unit cools down, it closes the relay & connects the circulator to the oil furnace again.

You'd need 2 relays -- one to connect/isolate the furnace & one to connect/isolate the coal unit.

I was thinking I should be able to do it with one relay. Do they make a relay that you can control 1 power out (to my circulating pump at the oil boiler) with 2 signal wires (one from the aquastat on the coal boiler telling both circulating pumps to run and one from the triple aquastat on the oil boiler telling the oil boiler circulating pump to run)?

BIG BEAM · Post by **BIG BEAM** » Sat. Oct. 04, 2008 10:18 am

They put that in because they were worried about thermal shock with the new boiler.That loop slows down the mono-flo system.Do you find the systems performance with the new boiler to work well? In other words when you turn up the thermostst do the radiators heat up quickly? I suspect they do with a 1 1/4" line feeding 2-1" mono-flo loops.I'm just guessing on the piping size of the loops.
DON

Plumbing and Wiring Help Needed

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