Pump sizing

rico7467

I have an outdoor wood furnace (open loop)
There is supply of 150' of 1 1/4 to the house then it enters an 1 1/4 manifold which supply's two runs 0f 20' of 1" to my furnaces which are both in my attic (ranch house)
They go up 12' then to each furnace heat exchanger which is 150'000 btu 1" ports.
Then they go back to the bottom of the wood boiler which holds 250 gallon of water.
Can someone tell me what size pump would circulate this?
Thanks

rico7467

I ordered a taco 007-sf5.....do u think it will be sufficient

Ironman

Are you using a heat exchanger to isolate the house loops from the wood boiler and keep them pressurized?

And no, I don't think it's sufficient. There's a lot more to sizing than just knowing your line sizes. It all starts with knowing the heat loss of the house and how many btu's are needed. But if you're not pressurizing the house side, there's no reasonably sized hydronic circ that will work right.

icesailor

Because it is a "Open" system, you need a pump that will generate enough "Head Pressure" to pump from the water level of the tank (which is lower) to the highest level in the attic, And add resistance for the piping. If it is a "Closed" system, the altitude pressure is pretty much canceled. There's a lot more calculations than a 007 will do. You need to know how many GPM's you need at what head pressure.

Gordy

Was the really answered?

icesailor

Was there enough information provided for a good answer?

rico7467

A plumbing company told me that I might have to put a plate exchanger in the baserment and make the woodburner an open system then make the house side a closed system with seperate pumps because that's the only way to get pressure to circulate up the 14' to the attic. Thoughts?

Gordy

Ironman answered that with his post....yes you should do that.

Ironman

rico7467 said:

A plumbing company told me that I might have to put a plate exchanger in the baserment and make the woodburner an open system then make the house side a closed system with seperate pumps because that's the only way to get pressure to circulate up the 14' to the attic. Thoughts?

That's exactly what we've been trying to communicate. A plate HX of SUFFICIENT size, another circ, fill valve and backflow preventer, expansion tank and an MRB ( air separator) along with a means of purging air.

But we'll need the btu requirements of the house along with other data for sizing.

icesailor

rico7467 said:

A plumbing company told me that I might have to put a plate exchanger in the baserment and make the woodburner an open system then make the house side a closed system with seperate pumps because that's the only way to get pressure to circulate up the 14' to the attic. Thoughts?

Your "plumber" doesn't have a comprehensive understanding of how pumps work.

Gordy

I'm sure something was lost in the translation. In that he needs to isolate through an HX to be able to have the system side pressurized.

rico7467

Ok what size pump would circulate the 300 feet loop on the woodburner side? I know your gonna day I need to know how many btu I'm using but I plan on using every bit I can with more accessories.

rico7467

Is my grundfos 15-58 too small

SWEI

Look on p.7 of this (numbers will work for any ASTM-compliant SDR9 PEX) to figure the head loss to and from the boiler. With no buffer tank in the house, the maximum flow will be at the design day heat loss for the house or the peak DHW demand if there is an indirect or other HX for that. You'll have to pick a ΔT as well.

You really should consider having someone design this properly for you. Boiler return water protection is critical in this application.

Gordy

yes its to small.

Use page 6 of that manual SWEI posted you have 1 1/4" pipe

Gordy

You need to know.

Btu output of boiler.

What water temp those fan coils need to put out the btus needed for the space they will heat.

What average water temp you can live with to size the flat plate hx.

Example

At 15 gpm with 40* delta will move 300k
that would be 160 AWT. 180 supply 140 return.
12.3' of head for 300' of 1 1/4" pex

As you can see more info is needed it's not as simple as telling you what pump you need.

Even my head loss has no calculations for pressure drop for fittings etc. just 300 ' of pex at 180* water

jlgelectric

not sure if you got your answer yet on the pump size but I am pumping (open system) up hill 300 feet with elevation difference or 60 feet. there was no need for me to have heat exchanger to have a closed system at the house. im using two taco 2400-20-wb pumps

SWEI

The 2400-20-WB is a 1/6 HP PSC motor pump. Probably draws about 200W when running. Two of those would constitute a rather high pumping load. Close the loop and you could probably cut that by 75%, possibly more depending on pipe losses.

Gordy

It's not a question of can it be done. It's a question of how to do it efficiently. Meaning costly pumps to operate. your chugging 368 watts at the electric meter with both pumps running

Gordy

Sorry Kurt.....

jlgelectric

wouldn't I have to install another hx in the back of my outdoor boiler?

Gordy

Yes

SWEI

No apology necessary. We're just echo..echo..echoing at times.

For a 392 Watt continuous load, just multiply your electric rate (including taxes and fees) per kWH by 265 and you'll see what it costs you per month.

hot_rod

Good info on OWF piping and the issues with open systems in Idronics 10.

http://www.caleffi.com/sites/default/files/coll_attach_file/idronics_10.pdf