Domestic hot water options with remote boiler

Re: Domestic hot water options with remote boiler

PostBy: biggreen1 On: Wed Jul 09, 2008 7:50 pm

LsFarm wrote:The next plumbing method is a little more complicated, but will give you constant hot water.. You plumb the coal boiler to the oil boiler with it's own supply and return lines.. Hopefully you can fine unused ports on the oil boiler, otherwise adding a 'TEE' to the existing supply and return will be needed. In the loop that is created between the coal and oil boiler, you install a small circulator, like a Taco 007. I would run the circulator 24/7, they burn .78 amps.. costs about $10/month in electricity.. But you can add an aquastat to control this pump if you wish. The aquastat on the oil boiler should be set about 20-30* lower than the coal boiler's aquastat. Or some folks just put a switch on the oil burner to turn it off..


LsFarm,
I'm trying to understand what you mean with this setup. I understand about having the two boilers constantly circulating between the two and possibly using a aquastat so it doesn't need to run all the time. But the t - setup has me confused if I also want to keep the oil boiler usable for house heat. The way I'm picturing it I would not have to T the hot supply line from coal to oil boiler. But after the oil boiler I would need to T it to the house radiator system with a circ pump and and the other part of the T would be to bypass the house radiators when only keeping the oil boiler hot for domestic water. It would need to be wired so that when house heat is called for it's circ pump would turn on but the other circ pump (the one that is a constant circ for DHW) must turn off at the same time or a lot of potential heating will be just going straight back to the boiler. Also, when/if the oil boiler starts the circ pump for the DHW bypass should also be off automatically. My house is old/large but only only has one zone. I'll try and post a diagram if this doesn't make sense. BG
biggreen1
 

Re: Domestic hot water options with remote boiler

PostBy: biggreen1 On: Thu Jul 10, 2008 12:00 am

Here is a diagram of my thinking for using the oil boiler for DHW.
1. For DHW only - no heat to radiators, Circ pump 1 off, circ pump 2 on always or with a aquastat
2. For DHW and heat in house - Circ pump 1 on, Circ pump 2 off
3. Coal boiler is not working and oil boiler kicks on - circ pump 1 on when heat is called for, circ pump 2 off
I've simplified my radiator plumbing (there are 4 branches) but there is only 1 zone controlled by pump 1

Where am I going wrong?
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Re: Domestic hot water options with remote boiler

PostBy: traderfjp On: Thu Jul 10, 2008 12:46 am

Freddy: Good job wearing the little lady down. I have a lot of toys using that method. It wasn't easy but I convinced my wife we needed speakers that are usually used in theaters.
traderfjp
 
Stove/Furnace Make: Alaska
Stove/Furnace Model: Channing 3

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Re: Domestic hot water options with remote boiler

PostBy: franknbaum On: Thu Jul 10, 2008 1:47 am

It looks like it will work. I have four possible short falls
1. Heat loss from the oilburner stack.
2. Maybee a backflow preventer by pump 2 so your heat zone does not loop itself
3. It takes a while for a coal fire to ramp up under heavy DHW use your oil burner will fire up
4. Zone valves and piping to isolate coal boiler for servicing
franknbaum
 
Stove/Furnace Make: alaska
Stove/Furnace Model: channing III

Re: Domestic hot water options with remote boiler

PostBy: biggreen1 On: Thu Jul 10, 2008 1:01 pm

"It looks like it will work. I have four possible short falls
1. Heat loss from the oilburner stack.
2. Maybee a backflow preventer by pump 2 so your heat zone does not loop itself
3. It takes a while for a coal fire to ramp up under heavy DHW use your oil burner will fire up
4. Zone valves and piping to isolate coal boiler for servicing"

Franknbaum,
1. I guess there is nothing I can do about that one
2. Before or after pump 2 (I would guess after)
3. I've read that here before and I suspect that may be a problem. I know this setup will not be the best but I thought it may work OK. Even if I'm not drawing DHW out of the oil boiler, would the oil boiler kick on because of heat required in the house (until the coal catches up)?
4. This boiler will be about 85' away from the oil boiler 35' of piping under ground. Do you think I should put isolation valves in the house and also in the garage at the boiler?
Thanks, BG
biggreen1
 

Re: Domestic hot water options with remote boiler

PostBy: billw On: Thu Jul 10, 2008 2:15 pm

I'm doing a similar setup. I'm running the oil and coal units in series, DHW is in the oil unit. I plan on having a pump circulating the water between the two boilers running constantly. The oil burner aquastat will be set at the minimum setting. I'm going to start the coal unit's aquastat low limit at 140. This should keep both boilers around 140 all the time. If the oil unit fires up I'll raise the coal unit's low limit until I reach a temp that keeps the oil unit off. I'm going to use a power damper on the oil unit to keep heat loss up the chimney to a minimum. Hopefully this works, if not I'll be looking for a better solution for next season. The most important thing for me is to not burn any of that 4.50 a gallon oil this winter.
billw
 
Stove/Furnace Make: EFM 520
Stove/Furnace Model: GOODBYE OIL COMPANY

Re: Domestic hot water options with remote boiler

PostBy: LsFarm On: Thu Jul 10, 2008 2:18 pm

billw, that's the setup that is the easiest to plumb and wire, with a little participation on your part, you should be able to tune the aquastat temperatures to make the system work per your plan.

Greg L
LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Re: Domestic hot water options with remote boiler

PostBy: franknbaum On: Fri Jul 11, 2008 1:27 am

1. I guess there is nothing I can do about that one. like billw said a power damper on the oil burner if code allows
2. Before or after pump 2 (I would guess after) I would go with after pumps like to push water[/color]3. I've read that here before and I suspect that may be a problem. I know this setup will not be the best but I thought it may work OK. Even if I'm not drawing DHW out of the oil boiler, would the oil boiler kick on because of heat required in the house (until the coal catches up)? Maybe go with a water to water heat exchanger like ls farm on your tempering tank.4. This boiler will be about 85' away from the oil boiler 35' of piping under ground. Do you think I should put isolation valves in the house and also in the garage at the boiler? For convenience both ends, they are not that expensive use 1/4 turn ball valves not gate valves.
franknbaum
 
Stove/Furnace Make: alaska
Stove/Furnace Model: channing III

Re: Domestic hot water options with remote boiler

PostBy: biggreen1 On: Sat Jul 12, 2008 11:16 pm

Most here recommend having the loop between the boilers running constantly. In my plan I was going to turn off that loop when there is a call for heat at the radiators. As I keep pondering about this, I guess it will not really hurt the BTU output capacity of the radiators to keep pumping hot water back to the coal boiler through the continuous loop because this water won't need to be heated in the coal boiler and it will be coming back through the loop again anyway? Make sense???
biggreen1
 

Re: Domestic hot water options with remote boiler

PostBy: coalboy On: Sun Jul 13, 2008 7:53 am

By looking at the diagram.It looks like pump 2 should turn off, when pump 1 calls for heat.If not,they both will be fighting for the water..I'm not saying i'm right,but that is what it looks like to me. :confused:
coalboy
 
Stove/Furnace Make: AxemanAnderson
Stove/Furnace Model: 1949 AA130

Re: Domestic hot water options with remote boiler

PostBy: Sting On: Sun Jul 13, 2008 10:11 am

biggreen1 wrote:Most here recommend having the loop between the boilers running constantly. In my plan I was going to turn off that loop when there is a call for heat at the radiators. As I keep pondering about this, I guess it will not really hurt the BTU output capacity of the radiators to keep pumping hot water back to the coal boiler through the continuous loop because this water won't need to be heated in the coal boiler and it will be coming back through the loop again anyway? Make sense???



If you are referring to Primary Pumping - yes and yes

But there are many unique pumping methods discussed. Some of mine are the worst out of pipe experiences :lol: !
Sting
 
Other Heating: OBSO Lennox Pulse "Air Scorcher" burning NG

Re: Domestic hot water options with remote boiler

PostBy: biggreen1 On: Tue Jul 15, 2008 9:22 pm

Ok,
1.1/4 turn ball valves on both ends.
2. Back flow preventer after pump 2.
3. I'll check on the power damper.
4. Pump 2 running constantly.

Questions:
1. My coal boiler (in the garage) will be lower than the oil boiler and I'm going to have the piping travel down hill all the way to the coal boiler. I should have drain valves at the low points at the coal boiler correct?
2. I'm planning on using the special antifreeze just to be sure it doesn't freeze. I know this is a dumb question for you guys but I need to ask, how do you get it in the system?
biggreen1
 

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