New OWB: Pump size question?

Andy M · February 13, 2012, 09:35:56 PM

I bought a used Aquatherm OWB at a really good price. It was a unsheltered unit with nothing on it, it was just the boiler. I bought all the new parts and installed them on the boiler, and I'm almost finished with the shelter now. I've talked to a few people about pump size and the type of underground pex they have used and get so many different answers. I want to run the boiler around 140 feet from the house. Is a Taco 007 pump to small to run to the heat Exchanger? The local CB dealer told me to go to a 009 pump, but this is already after I bought the 007. They said just keep the 007 as a spare in case of an emergency. The also sell the good thermo pex at around $11.50 a foot. I think I'm going to go that route to save me from digging back up some cheap pex that others sell. Any suggestions will help. I'm anxious to get this thing up and running. Thanks

chevytaHOE5674 · February 13, 2012, 10:16:10 PM

The actual PEX tubing in the thermo-pex and the cheaper stuff is likely the same. The thermo-pex is just better insulated than the type that is just wrapped in foam. Having said that I have the cheap foam wrapped stuff as that's really all that was available when I put my OWB in, and I experience very little heat loss underground (but my pipe is 7 feet down there).

As for pumps my boiler came with a 009 and it wouldn't push through the two heat exchangers. So I went with a bigger pump (not sure the model off hand) and has been fine since. I still have the 009 for a spare, it will push through one heat exchanger at a time but not both (so in an emergency i could circulate water through the furnace for heat, just no domestic hot water).

brokentoe · February 13, 2012, 11:41:12 PM

Welcome! I also have the thermopex in the ground and went about 2 feet down. I have an 80 foot run from my eclassic to the house. I have a gauge in the supply line at the furnace and another gauge in the supply line as it comes in the house. less than 1 degree heat loss! I researched different types of insulated lines prior to purchase and just didn't want to risk of having to dig up water logged or poorly insulated lines.

xlogger · February 14, 2012, 06:40:13 AM

I'm getting my furnace this weekend. The dealer said my 009 pump will work for me. See if you guys think it will? I'm 70 ft from house about 5 ft lower than where I'm going in with the ditch adding another 4-6 ft. Hot water is on same level but furnace is in attic, about 21 ft higher. The 009 pump suppose to lift 32 high and the next larger pump will only push around 24-25 ft with more gallons per minute.
Has anyone tried this?

thecfarm · February 14, 2012, 06:46:21 AM

AndyM,I run 007 and I'm only 30 feet from the house,but what do I know. Can you ask where you are buying them from? Someone should know on here too.
I'm not ignoring you xlogger,I have no idea.

Andy M · February 14, 2012, 07:45:34 AM

The guy I bought the OWB from ran a 007 pump on it and he was probably 100 ft from the house. He heated the house with a water to air heat exchanger like I am going to do plus his hot water heater. I'm thinking the the 009 would be the way to start because I don't really want to shut this thing down to change a pump that isn't big enough to start with. That is why I am asking everyone here because all of you have the experience since your OWB have been up and running. Thanks again for the help.

doctorb · February 14, 2012, 07:59:53 AM

Andy- Welcome to the Forum.

I can't answer your pump question. But to make sure you get the answer, I changed the title of your thread to reflect what info you are trying to gather.

mrwood · February 14, 2012, 09:18:35 AM

When I put in my OWB in aug. all of the sizing pointed me towards an 007. But my dealer had told me that he didn't recommend it. Something Bout the 009 purges the air better and does not become airlocked. IMO go with the 009. Although it does suck being you already bought a 7 and these thing are not cheap

DeerMeadowFarm · February 14, 2012, 10:25:30 AM

I'm 100 feet from the house, used thermo-pex (pita to bend!) and I have a 009 pump in the house to circulate the OWB water through the heat exchanger and back and another 009 to circulate the water from the oil-fired boiler through the heat exchanger. I have a 007 (not in service yet) that I plan to use in my barn to circulate OWB water through a modine heater. My dealer asked how high I planned to mount the Modine; he said the lower the better if I was using the 007.

Based on that; I'd say use the 009. My $.02.....

chevytaHOE5674 · February 14, 2012, 10:34:21 AM

Quote from: Andy M on February 14, 2012, 07:45:34 AMbecause I don't really want to shut this thing down to change a pump that isn't big enough to start with.

Should have flanges with shut off valves on each side of the pump. That way you can shut both valves off and change the pump out in a matter of minutes without letting the fire go out or draining anything.

doctorb · February 14, 2012, 12:22:55 PM

I have never had to do it, but I do not suggest changing the pump out with the fire going. Without continuous circulation of the water, the furnace can boil.

reride82 · February 14, 2012, 12:39:27 PM

Quote from: xlogger on February 14, 2012, 06:40:13 AM
I'm getting my furnace this weekend. The dealer said my 009 pump will work for me. See if you guys think it will? I'm 70 ft from house about 5 ft lower than where I'm going in with the ditch adding another 4-6 ft. Hot water is on same level but furnace is in attic, about 21 ft higher. The 009 pump suppose to lift 32 high and the next larger pump will only push around 24-25 ft with more gallons per minute.
Has anyone tried this?

Since this is a circulation pump, does it matter how high the water is pumped, besides initial pipe filling the net head on the pump is zero neglecting friction loss. The pump is a circulation pump and the water may have to travel up, but also acts as a siphon on its return trip to the boiler. Just my $0.02.

Andy M · February 14, 2012, 07:39:53 PM

I have Taco isolation ball valves installed. But I agree with not trying this when the boiler is firing. It probably wouldn't take long to boil over without the water circulating.

chevytaHOE5674 · February 14, 2012, 09:37:56 PM

Last pump I changed was done in less than 10 minutes. The gauge on my stove hardly moved enough to notice in that time period. I just let the stove burn down and went to work.

Holmes · February 14, 2012, 10:56:11 PM

Reride82 you are right it is a circulator not a pump, but everyone calls them pumps including me.
Height makes no difference but total length of pipe, pipe size, fittings, and boiler or heat exchanger add up to the amount of friction loss {head} needed to move the correct amount of water thru the pipes to deliver the heat.
300' total lenght of 1" pex tubing delivering 12 GPM {120,000 BTU,s}is 22.89 feet of head. A 009 pump will deliver 4.5 gpm at 23' of head {45,000 btus} . You will get some heat but not enough.
A 0011 pump will deliver 13 gpm at 23' of head {130,000btus}.
These figures do not include head loss for a boiler or heat exchanger, but it does give you an idea that an 007 pump is way to small , an 009 pump will work but it is not the right choice. You do need a larger pump an a 0011 is the better choice with the info you have provided. If you want heat you need to pay the price for the pump to get your heat delivered into your house.
Now if you bought a smaller diameter pipe like 3/4" you will need a bigger pump. The smaller the pipe the more friction loss so a bigger pump is needed. Holmes

xlogger · February 15, 2012, 06:15:09 AM

I was told by the dealer that a 0011 pumps more volume but will not push the water as high as the 009.

Corley5 · February 15, 2012, 07:24:36 AM

http://www.pexuniverse.com/content/how-size-circulator-pump

This is the info I used to size my circulators both the main one and for the zones. It takes the guess work out of it.

thecfarm · February 15, 2012, 07:28:29 AM

Doctor,just so you know it's very EASY to change pumps. I had some trouble with mine and changed them 3 times.Took me 15 minutes the first time because I had no idea what I was doing. Just turn off 2 valves,4 bolts,2 o'rings and that's about it. My other IWB I would have to purge the air out of it,it was pressurized. My OWB I don't have too.

Holmes · February 15, 2012, 07:29:16 AM

Quote from: xlogger on February 15, 2012, 06:15:09 AM
I was told by the dealer that a 0011 pumps more volume but will not push the water as high as the 009.

You do not need height you need to push against friction loss and restrictions. What goes up also comes down so it balances out. An 009 will not give you enough flow to get all the heat out of the boiler and into the house.

Holmes · February 15, 2012, 03:09:07 PM

Sorry xlogger. I thought you were the OP. The 009 will handle your situation, you have half as much piping as AndyM.

Andy M · February 15, 2012, 03:30:22 PM

The Aquatherm boiler is a pressurized system. It is supposed to run between 10 and 15 psi. Not that any of that makes a difference between each type of boiler, I really do appreciate everybody giving the good advice on this forum. Everyone that is running their OWB has had some type of problem or solution that has been helpful to me being new to this and I just want to make sure I get it right the first time. Thanks again.AndyM

Andy M · February 27, 2012, 09:16:31 PM

Got my Thermo-Pex last week. I went the better route to hopefully save me later. Going to install the heat exchanger and connect hopefully on Wednesday. It's been a long process getting this thing the way I want it. If I could figure out how to post pictures, I would. Even though I'm installing an Aquatherm, the local CB dealer has been a real help since I bought the Thermo-pex and fittings from him.