Running two pumps

General Outdoor Boiler Discussion
larryjbjr
Posts: 34
Joined: Mon Jun 12, 2017 7:17 pm
OWB brand: Johnson
OWB Model: Little John
Location: A bit north of Milwaukee WI

Running two pumps

Post by larryjbjr » Tue Sep 12, 2017 10:16 am

OK, I am wondering if this will work. I only have one set of 1 inch pex running to and from my boiler. However I am thinking to run two heat exchangers, one for my hot water as well as one for my propane boiler. So I thought about if I could just tie into the supply before it gets to my heat exchanger for my boiler and run that with a separate pump to the heat exchanger for the hot water heater. It is about 80 feet from the boiler to inside the basement. From there it would be another 12 feet to the primary heat exchanger and about 8 feet to the water heater heat exchanger.

Would someone take a look at my diagram here and see if they think it will be OK?

I'm mainly wondering whether having another pump like that will hinder or help the flow of water.

Image

RSI
Posts: 303
Joined: Mon Jun 23, 2014 8:51 am
OWB brand: HeatMaster
OWB Model: G200
Location: South central Wisconsin
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Re: Running two pumps

Post by RSI » Tue Sep 12, 2017 8:01 pm

The way it is drawn would not be good for the pumps and you would probably not get water to the bottom heat exchanger.
Is there a reason you can't just put them in series? If you want to turn one of them off when heat not needed then you could connect it similar to the drawing. The difference would be to put both tees in the same line and it would have to be after the first pump.

Bull
Posts: 56
Joined: Sat Oct 29, 2016 9:18 pm
OWB brand: Central Boiler
OWB Model: 4436
Location: Southern Indiana

Re: Running two pumps

Post by Bull » Wed Sep 13, 2017 9:06 pm

I would run it to the water to water heat ex. (water heater) then to the heat exchanger on the propane boiler then back to the owb

larryjbjr
Posts: 34
Joined: Mon Jun 12, 2017 7:17 pm
OWB brand: Johnson
OWB Model: Little John
Location: A bit north of Milwaukee WI

Re: Running two pumps

Post by larryjbjr » Thu Sep 14, 2017 9:35 am

The main reason for not putting them in series is because I don't want to have anymore head for my pump to go against.

Maybe I'm just overthinking this though. I can try that for this winter and see how it goes.

outdoorboilerforums
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Re: Running two pumps

Post by outdoorboilerforums » Thu Sep 14, 2017 8:06 pm

If there is two much head pressure for the pump in series then put the two pumps in series.

larryjbjr
Posts: 34
Joined: Mon Jun 12, 2017 7:17 pm
OWB brand: Johnson
OWB Model: Little John
Location: A bit north of Milwaukee WI

Re: Running two pumps

Post by larryjbjr » Fri Sep 15, 2017 10:07 am

outdoorboilerforums wrote:If there is two much head pressure for the pump in series then put the two pumps in series.
I don't think I knew that I could do that. And that would work fine?

larryjbjr
Posts: 34
Joined: Mon Jun 12, 2017 7:17 pm
OWB brand: Johnson
OWB Model: Little John
Location: A bit north of Milwaukee WI

Running two pumps

Post by larryjbjr » Fri Sep 15, 2017 2:49 pm

If I did that, could I simply T off after both pumps and go to the water heater? Or do I have to put the heat exchangers in series?

larryjbjr
Posts: 34
Joined: Mon Jun 12, 2017 7:17 pm
OWB brand: Johnson
OWB Model: Little John
Location: A bit north of Milwaukee WI

Running two pumps

Post by larryjbjr » Fri Sep 15, 2017 2:53 pm

Also, do the pumps have to have any kind of minimum distance between each other?

RSI
Posts: 303
Joined: Mon Jun 23, 2014 8:51 am
OWB brand: HeatMaster
OWB Model: G200
Location: South central Wisconsin
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Re: Running two pumps

Post by RSI » Fri Sep 15, 2017 4:55 pm

You could tee off but usually it makes more sense in series. If you split them then you are pumping a lot of water that never gets used since the water heater is only intermittent use. There are a couple other connection options you could do such as secondary loop or monoflow tees.

What model pump are you planning on using?

It would be best if both were before the first heat exchanger. You could just use one larger pump if needed instead of two in series.

What is the total length of pipe round trip if you put both heat exchangers in series? What size pipe do you have?
Are both heat exchangers going to be plate type? What sizes are each? How far is it from where the first heat exchanger will be to the second?
What type of heat does the house have? (eg. baseboard, radiators, radiant, etc)

larryjbjr
Posts: 34
Joined: Mon Jun 12, 2017 7:17 pm
OWB brand: Johnson
OWB Model: Little John
Location: A bit north of Milwaukee WI

Re: Running two pumps

Post by larryjbjr » Sat Sep 16, 2017 9:30 am

RSI wrote:You could tee off but usually it makes more sense in series. If you split them then you are pumping a lot of water that never gets used since the water heater is only intermittent use. There are a couple other connection options you could do such as secondary loop or monoflow tees.

What model pump are you planning on using?

It would be best if both were before the first heat exchanger. You could just use one larger pump if needed instead of two in series.

What is the total length of pipe round trip if you put both heat exchangers in series? What size pipe do you have?
Are both heat exchangers going to be plate type? What sizes are each? How far is it from where the first heat exchanger will be to the second?
What type of heat does the house have? (eg. baseboard, radiators, radiant, etc)
Right now I have a bell and gossett nr22. I was thinking of just buying another one of those. Or a grunfos

I have 80 feet of 1 inch pex A going from the OWB in to the basement, from there it would be around 10 feet to the 20 plate heat exchanger for the water heater, then another 15 feet to the 40 plate heat exchanger for the boiler.

My house is heated mostly by cast-iron radiators. I also have two 10,000 BTU kickspace heater's, and about 30 feet of baseboard heaters.

So if I put everything in series it would be around 210 feet of 1 inch pex A round trip.

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