Help with OWB, is my pump right?

[Timbercreek]

Hi folks,
My boiler is a heatmor 100cs.
Roughly 125' of 1" thermopex each way, boiler is 125 from house. Buried 3' down
Taco 0010 at the boiler
100plate sidearm in the house,
Taco 007 moving inside water thru oil furnace.
Heats house fine if one zone is calling or its warm out. Very slow heat recovery if its cold out.
Is my taco 0010 too small for 125' run(250' loop?)
So i have cheap clipon thermos at all 4 points and havent busted out the ir thermo yet.
Boiler says 72 out 50 return(celsius) guessing the 150 degree ambient air affects the gauge, as leaving rear door open drops both gauges
Wood side of Heat exchanger in house says 42 in 32 out (celsius)
Oil furnace side says 32 out 32in, sometime 30 in
Heat exchanger is plumbed so wood hot goes in the top and the oil hot comes out there,
Wood return comes out bottom and oil cold goes in there.
Wood Boiler was cycling on at 150 and off at 185 farenheit.
Wood boiler is 6' higher then sidearm as the sidearm is in basement.
Oil furnace tied to sidearm via 1" copper.
Any and all opinions are welcome.
Plumber says the 0010 is high flow low head, says i need a high head pump, 0011 or 0013.
Saw some instances of 0013 cavating on 1" line on 300' loops.

 

[NSMaple1]

I assume when you say sidearm, you mean flat plate HX?

Not 100% about the pump, but those temps sure seem to show that something isn't right.

Boiler out is 72c (160f), and the other end of the underground (Wood HX In) is 42c (110f)? That's a 50f difference - huge. Like off the charts huge. Then looking at the oil side of the HX, there is next to no heat rise. So putting 2 + 2 together, it seems there is little flow through the underground.

You can get an idea on what pump you should be using here:

http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf

The main unknown would be what is the headloss in your plate exchanger? Plus all other fittings in the loop.

You should also know the heat demand of the house to do it right, that will tell you GPM you need.

But if you didn't want to get into math, you could just swap in a 0011 & see what happens.

An airlock or some other kind of obstruction might also be a possiblity - so inspect very carefully for high spots in the piping where air can't get out. You might need to cut in a bleeding spot at a high point if you've got high points.

(Is this a new install?)

 

[Timbercreek]

Kinda sorta new install. House had a central boiler, husband repod it, i installed the heatmor and hooked it up.
Didnt ever look at the owb pump, it was already on there. So anyway, without knowing what the head is on the plate exchanger, 100 plate from central, old owners went 1 step above the recomendation. 1.25" connections on the plate.
My supply house says i have 30' of head without the exchanger and a 0013 will barely get me 10gpm.
He also cant believe the 0010 is even moving water, and if it is its only doing 1 or 2 gpm so ive been heating the house with like 20,000 btus!!
Hence the boiling i hear if theres a roaring fire in the box(lumber, kindling,pine) boiler is always full of water, but im guessing with such little flow there are times not enough heat is removed before the cycle shuts down.
Boiler seems to work fine, just not getting heat into the house fast enough, and id say its def the pump.
Ordered a 0013 stainless. See what happens from there.
Supply house wanted me to do a 2400-45 and im like dude, thats 4 amps at 115v versus 2. I dont think so.

 

[tawilson]

Why the big differential on the wood boiler? Is that what they recommend?

 

[Timbercreek]

They want it 165-185.
I adjusted it yesterday, and its now doing 170-185f.
But maple mixed facts, the boiler in and outs dont match the heat x in outs on boiler side.
Today im running 82c out of owb and 62in.
Thats only a 20 degree celsiues spread.
He was taking the highest boiler and lowest x and making the spread for 50f.
Its never been that bad.
20 degree celsius has always been the spread at boiler and only 10 degrees at the boiler side of xchanger.
The oil furnace loop is coming in at 32 and out at 34 celsius at xchanger.
Need more flow to get BTUs into the house. Higher temp at the exchanger should get more heat into the oil furnace loop.

 

[tawilson]

Maple did mention air in the system. Does your hx have a way to vent? I had air in mine until I replumbed it and added a vent.

 

[Timbercreek]

I have boiler drains on both sides of heat exchanger, and y strainers with boiler drains there.
Drained em down a bit checking for scale etc, no air.
Also the boiler is the high point and self vented. Air usually makes noise too.
Now that i have the math, i really think he was right, its the pump. He just doesnt do OWB every day so wanted some more opinions.
And was trying to go with the 11, but now that the supply house wants me to get a 45, ill take the 13!!!!
2amps 24hrs a day is enough. Dont need 3.6.

 

[NSMaple1]

But maple mixed facts, the boiler in and outs dont match the heat x in outs on boiler side.
Today im running 82c out of owb and 62in.
Thats only a 20 degree celsiues spread.
He was taking the highest boiler and lowest x and making the spread for 50f.
Its never been that bad.
20 degree celsius has always been the spread at boiler and only 10 degrees at the boiler side of xchanger.
The oil furnace loop is coming in at 32 and out at 34 celsius at xchanger.
Need more flow to get BTUs into the house. Higher temp at the exchanger should get more heat into the oil furnace loop.

Didn't you say in post 1 that boiler supply (out) was 72c, and the inlet on the supply (wood) side of the HX was 42c? So that's 162f to 108f - a 54f degree drop between them, and the only thing between them is the underground piping. Right? It should only be a couple of degrees with Thermopex. Which means there is next to no flow.

I assume your boiler has a bypass loop or return temp protection? That explains the smaller drop across boiler supply & return.

If not, it should.

 

[Timbercreek]

No loop or return. High limit shutdown on temp, and constant loop on circulation, no modulating.
So if the owb gauges set a range, thats the max it can be. It cant leave the heat exchanger at 38 and be 50 at the furnace, because if it is thats some serious heat soak!! Would mean the return water was siphoning 12 degrees from the hot side!!

 

[NSMaple1]

How do you explain your boiler temp readings then? Where exactly are you measuring them?

Also, are you pumping from the boiler on the lower fitting? And returning to the upper one?

 

[Timbercreek]

Its either the bleedover theory, or the ambient heat of their surrondings throwing em off. The 2 on the back of the boiler live in a 150 degree closet, the 2 in the basement live in 58 degree climate control.
If i leave the back of the boiler open, the 2 there will both come down a few degrees

 

[NSMaple1]

Can you verify which boiler port you're using for supply, & which one for return? And where you're measuring temps? Sounds like close to the boiler - so even if there is no flow through your loop, you would get some heat convecting out of the boiler into the piping, that might be affecting the temp readings too.

The manual I found online for a Heatmor 100 suggested 8gpm flow through the boiler for good internal mixing. In which case I think the 0010 is definitely too small.

 

[Oxford]

I can't find the head loss for Thermopex online, but if you use the standard for 1" pex-al-pex and add the standard head loss of a plate exchanger, at 10 gpm (100,000 btu/hr) you're at roundabout 34' of head. If you use the Taco selector, the 45 is what's recommended. You'll doubtless argue, but it is what it is. That 0013 shows about 5 gpm at 30'. Since you'll have constant flow and most homes don't ever need 100kbtuh, you'll probably sneak by, but you won't have anything like a good design.

 

[Timbercreek]

Wow. Thank you.
The owb is plumbed so the top port is return and the bottom port is source.
And yes the boiler gauges are very close to the tank. Return is maybe 8" of brass away, a nipple a 90 and a long nipple
Outgoing is similar, right by the pump. On 1.25" brass
I got a smoking deal on a 0013 stainless, so im going to try that, and if i still lack for heat i can put the 45 on there.
My supply house quoted me out at 366 and 566,13 vs 45
I found a brand new 13 stainless for 266 shipped to me. Half the price of the 45.
My biggest concern about slapping the 45 on there is the 1" line and running such a big pump to fight small pipe.
Where did you get the head numbers for the exchanger? I was looking on central boilers site last night,
Going by there chart i have the 70 plate, biggest there is on 1.25" ports
Was like.43 loss x 2.3? So like 1 foot of head?

 

[NSMaple1]

Sounds like your boiler connections, pumping direction & pump location are all good. And yes, it should have purged air, although we can't be there to look for possible high air-trap spots.

I would say your underground piping was undersized from the get-go. Should have been at least 1-1/4". Seems to be a rather common oversight on many OWB installs. But, at this point, it is what it is - at least it's Thermopex and it shouldn't lose much heat.

Something else you might be able to try, if the 0013 doesn't work out good, is add the 0010 to it & run them in series. Maybe put it inside the house, on the inlet of the OWB side of the HX.

More info, looking back at the Taco sizing doc linked above: The max flow rate for 1" Pex tops at 7.5 gpm. I.e., above that and the water moves 'too fast' (more than 4fps). That doesn't get you to the Heatmor recommended flow through boiler of 8gpm, but it's close - and I'm not sure of the implications of flow that is too fast, in your situation. So if we assume 7gpm, that gives 17' of head, just for the pex. Doesn't account for any fittings or the HX. The 0013 at 8gpm is good for about 28' of head. I think you'll be OK, but will be interested in the outcome. (There's also a possibility it might pump too fast, not being sure of head of the rest of the system & HX). Keep us posted.

 

[Timbercreek]

Im chasing fedex trucks down praying its on it. No such luck.
I am happy to see that getting the flow down brings the head down, so the 13 should be a pretty close match.
The 45 is a *****, big flanges hence why i didnt want it versus the 13. Cant just swap it in 4 bolts and a cord.
I have no idea what happens when u go over 4fps on pex. I know if you flow too fast on hydraulics it strips the liner out of the hose due to friction. No idea with water and pex.
I imagine its probably just a imaginary "wall" due to turbulence and friction. Cant got much higher.
And ya, 1" shouldnt be used on anything pushing 100 feet or more. Especially with a big heat load.
I was looking on another site and theres a guy running a 013 on 1" and it works, but its noisy. Guess it cavitates pretty bad trying to work.
I have also heard of guys putting the pump in the basement, but i just dont see it working that good if it was the sole pump. Push it to boiler, let gravity run it back to house? Weird.

 

[tawilson]

Here's another idea I've toyed with. If you still find you need more flow through the boiler for circulation reasons, could you take the old pump and connect to your extra in and outlets, assuming you have them, and just have it run when your boiler is calling for heat?
And I have bolted different pumps in series and it does give you a boost. Now I have one on either side of my heat exchanger. They are both Grundphos 15-55, adding in the second pump gained a couple gpm's according to the readout on the pumps.

 

[Oxford]

I don't think that fluid velocity will be an issue here. It might be noisy, but it should flow, and you're still under the 8 that generally starts causing premature wear. Since the system is open and relatively cool, it's likely that you will have cavitation issues, but having the pump as close to the boiler as possible should help- least suction restriction possible that way. I would be leery of putting dissilar pumps in series for a whole host of reasons.

 

[Timbercreek]

I wouldnt tandem pumps due to my.energy usage concerns, but if i did i would use the same pump so the flows matched.
Guy shipped my pump. Hope it gets here before the cold this weekend!!
Only coming from upstate, so it should be a day once he gets it to the carrier

 

[Timbercreek]

As far as flow for circulation reasons, yes, i could hook up the garage loop and use the 10 as its only 30-40' away, but the problem is burn time.
Im struggling to go 12hrs now, amd with my future plans to heat the garage to 50 and a greenhouse, the little 100 would want 4 fills a day.
Doing 3 now, a full load for overnight, and 2 short stacks during daylight hours. Burn whateva during the day, oak at night.
Looking for a 200 as upgrade next summer. 3ft firebox and longer run times. Dont really need the btu