Outdoor Wood Furnace Info
All-Purpose OWF Discussions => Plumbing => Topic started by: Scratch on October 11, 2017, 08:59:28 PM
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So I've had my CB6048 for like 7 years now and love it. I just started a fire today to burn some cardboard and scrap lumber up and noticed that it seems like maybe my pumps aren't working. I'll try to describe my setup:
My stove is outside, 100' away from the house.
The water comes in through 1' PEX and straight into a Taco 007-F5 pump (~3' below ground level)
About 10' later it goes into my forced air furnace heat exchanger.
Then it goes about 50' to another forced air furnace heat exchanger.
Then it comes all the way back again and goes back outside... but that PEX goes by two T's first, right before it goes outside again.
The first T sucks the water through another Taco pump...
Next is a mixing valve...
Then my 4 radiant heat floor loops.
And finally, back out the second T, then it's outside and back to the stove to get reheated.
Today, I got my water up to temp at 185, the PEX is too hot to hold onto for very long as it comes into the first pump and into the heat exchanger. But the Pex coming out of the heat exchanger is barely even warm to the touch... I'll call it room temp! If I shut the furnace fan off, it'll eventually heat up to hot, but as soon as the fan starts to blow past the HX, it cools down to room temp.
Both of my pumps I can feel are vibrating and warm, but I'm not sure how good they're pumping. I replaced both pumps less than 2 years ago. I have bleeder valves going in and out of the HX and they seemed to have no air in them.
Is there a way to tell if they're pumping enough?
Could there be an air bubble in the line somewhere and if so, how do I get rid of it?
Is there a way to manually prime the system somehow?
Nothing has changed in my system in like 5-6 years of great heating.
Any ideas?
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Definitely sounds like low flow for one reason or another. It could have an airlock, but then I’d think the HX shouldn’t heat up at all.
Goto the back of your stove, with the pumps running, shut the return valve off for a few seconds, then open it quickly, this builds a little more than normal pressure in the line then upon opening the valve gives any air an added push out, unless of course the air is stuck in the pump then you won’t hear any water rushing into the stove.
On my original setup I had my pump in the basement with the reasoning being if it ever goes out I won’t freeze my *ss off changing it. That was 2001, I’m still using that pump for my snow melt.
Sometimes and this is from personal experience, it can be a real booger to get any air purged from a pump in the basement, I was using a Grundfos with the bleed screw on it and sometimes still had issues. If you get a chance and if so willing, move that first pump to the back of the stove and air lock issues will just be a bad memory for the most part.
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I would agree with mlappin. It's possible that 007 can't pull an air bubble through. A slightly higher head pump pushing from the furnace will usually eliminate that issue. And an 007 has barely enough head at that distance to purge out. If you had a jumper to a domestic water line in the house it could be used to blast it out. Sometime air will lay in a high spot and barely trickle by.
I've seen an impeller break off and barely stir water. Drove me nuts. :)
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I turn my circulator pump on for a few minutes every 2 weeks during the off burning season. If I do not do this when fall comes the bearings are locked up and I must replace the pump as the bearings are sealed and not replaceable. Hope this helps in the future.
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The 007 is a low psi pump. For what you have to pump threw I would step up to a grundfos 26-99. Or taco 009. Or 0011.
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I found an easy way to bleed it and now it works. Hopefully I remember how I did it next time!
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If you ever replace it the 007 is really undersized for that long of a loop. A 0015 3 speed would do better. Or 15-58 Grundfos, B&G NRF22 or 25, etc. The 007 is a low head pump which drops velocity down to where air could possibly hang in any high spot.
Anyway, glad you got running, it's getting cold weather.
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If you ever replace it the 007 is really undersized for that long of a loop. A 0015 3 speed would do better. Or 15-58 Grundfos, B&G NRF22 or 25, etc. The 007 is a low head pump which drops velocity down to where air could possibly hang in any high spot.
Anyway, glad you got running, it's getting cold weather.
Thanks, I think I'll check into one of those and get a couple for spares. Anyone have any suggestions for where to find one at a low cost online?
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Supplyhouse.com, EBay.
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Is the grundfos 15 58 a replacement size pump for a taco 007? Seems like the tacos need replaced every couple of years for me.
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15-58 has a similar flow rate, but higher head pressure. Pushes air out better and pushes through restriction better. I like three speed pumps like it and the NRF-25 so I can adjust flow as needed.
But your needing to replace every few years may be a system design issue that a different pump might not solve. Would need more info.
But yes, the 15-58 is a good 007 replacement, in my opinion.
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I concur. The 15-58 is similar flow with higher head for longer distances and/or elevation changes and the 3 speed is very nice to fine tune your flow needs. The NRF-25 is slightly larger yet, and also does a great job. I've got 3 of them at my place with one being 9 years old and never an issue. Though there may still be something in your system causing your Tacos to burn out, I've found that 3-4 years is a pretty typical lifespan of even a proper 007 installation. Some get a lifetime out of them and some replace them twice a year. I have one customer that's been running an 007 for ~30 years to serve 2 zones of baseboard in his house actuated by zone valves. When neither zone is calling for heat, the pump deadheads. I was going to repipe it when I saw that and mentioned it to him, but he said it'd been working that way forever and now 4 years later it's still going!
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With 320'+ pipe in the system and multiple heat exchangers, the the 15-58 should flow a fair amount more than a 007.
I agree with the post above saying it should be a 26-99 though.
A 26-99 may not be able to be used on high speed with the pump that far from the stove but low or medium should be about right. I would not put a 0011 that far from the boiler. Too likely to cavitate.
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With 320'+ pipe in the system and multiple heat exchangers, the the 15-58 should flow a fair amount more than a 007.
I agree with the post above saying it should be a 26-99 though.
A 26-99 may not be able to be used on high speed with the pump that far from the stove but low or medium should be about right. I would not put a 0011 that far from the boiler. Too likely to cavitate.
Good advice. Moving the main pump to the wood furnace would help a lot of things.