Confirm my suspicions...........

[James Ascherl]

So its a balmy -11 degrees here south of Cleveland. I have a 3700 sq ft home. In the late 80s the oil boiler was replaced with an electric boiler. This is basically a giant version of an instant on tankless water heater. I have copper baseboard radiators. The last few days I noticed that the house was struggling to maintain the requested heat (When temperatures were still around normal) I then closed one of the 4 zones on a part of the house that is seldom used. A few hours later the house got up to 70 degrees. Today, the house temperature continues to drop. The Taco 111 series pump is running continuously, and the 5 coils in the boiler continue to kick on and off, but the radiators are barely warm. The piping exiting the boiler is hot to the touch. My suspicions are that the fins in the pump impeller are worn off or broken off and the water is not circulating correctly. I have not been able to hear water trickle inside the radiators that I would occasionally hear. The pump is silently cruising along with virtually no humming. Am I correct on my assumption?

 

[Wildo]

Probably. One of the burner techs at my work said something similar about our heating system. He recommended Grundfos circulators. Tacos just don't hold up like they used to is what he said.

 

[ewdudley]

Got a smaller Taco pump off ebay that had an impeller that was toast, so I can say there is such a thing as impeller failure.

(Does the system really need a 30 gpm pump?)

 

[James Ascherl]

Actually I'm hoping to just replace the impeller since the motor is working well. If I have to replace the whole pump, I need to find one that fits between the flanges (9").

 

[Wildo]

Actually I'm hoping to just replace the impeller since the motor is working well. If I have to replace the whole pump, I need to find one that fits between the flanges (9").

That is a helluva lot cheaper than a whole new one.

 

[James Ascherl]

Ewdudley, I don't know. That's what is on there now. I don't know squat about hydronics (which is why my wood boiler still isn't running.) I'm really good at swapping parts though lol

 

[ewdudley]

Ewdudley, I don't know. That's what is on there now. I don't know squat about hydronics (which is why my wood boiler still isn't running.) I'm really good at swapping parts though lol

There is just one thing to know about hydronics that very often will put you on equal footing with any supposed expert:

btu_per_hour = gpm * degF_deltaT * 500​

I think you could get a good estimate of the upper limit of the gpm needed by taking the maximum output of the electric boiler in kW, convert to btu per hour, then divide by 20 degF_deltaT times 500. 20 degF_deltaT is considered a typical temperature drop for baseboard, YMMV.

For example: One kW = 3412 btu per hour, so 30 kW = 102,364 btu_per_hour. Gallons per minute equals btu_per_hour divided by 500 times degF_deltaT, so 10.23 gpm = 102364 btu_per_hour / (20 degF_deltaT * 500).

Working the other way, 30 gpm at 20 degF_deltaT is 300,000 btu_per_hour, or about 90 kW.

 

[MarkW]

Have to factor head of his system into that as well, no?
I love hearing that a particular brand is troublesome once I've invested in that brand.

Was a great night to have pump issues!

 

[ewdudley]

Have to factor head of his system into that as well, no?

Yes indeed. If the pump was somewhere in the middle of its curve it would be moving something like 30 gpm. I believe the OP has four zones of baseboard. Normal maximum flow for each 3/4" zone would be 4 ft per sec, or 5.5 gpm, 22 gpm if all zones calling. Taco 111 is a flat curve pump, so even with all four zones flowing the pump would be working hard and moving not much water relative to pump capacity. If only one zone calling there would be a lot of mechanical energy converted to heat by way of agitation by the impeller, so it seems reasonable to speculate that the impeller would suffer.

I love hearing that a particular brand is troublesome once I've invested in that brand.

[Conventional] Taco pumps are very much tried and true, but they can be made to fail if you work at it.

 

[MarkW]

Taco pumps are very much tried and true, but they can be made to fail if you work at it.

haha, true. I'm doing my best to go the other route. I'm looking into delta P for the future, atm. Seems it could maintain proper flow indepent of the # of zones open but I'll save questions for another thread.

If only one zone calling there would be a lot of mechanical energy converted to heat by way of agitation by the impeller, so it seems reasonable to speculate that the impeller would suffer.

Yep, there is definately a problem with that scenerio. Sizing for worst case often ends in creating said worst case through oversizing.

 

[Pat53]

I have a Grundfos Alpha running on my 2 house zones ( upstairs and downstairs) and I love it. Even when both are calling for heat its nice and warm in the house. The best part is that with both zones calling for heat, its using 8 watts of electricity ! Each level of the house is 1500 sq ft.
Pat

 

[MarkW]

Nice to know, Pat. My new build should run with 4 zones.

 

[maple1]

I have a Grundfos Alpha running on my 2 house zones ( upstairs and downstairs) and I love it. Even when both are calling for heat its nice and warm in the house. The best part is that with both zones calling for heat, its using 8 watts of electricity ! Each level of the house is 1500 sq ft.
Pat

+1 on love for the Alpha. Absolutely sweet how it ramps itself up & down as zones open & close to maintain constant flow in each zone. An aside is the last power bill we got was the lowest ever for this time of the year. Not by much, but I have to think the Alpha played a small part in that.

I'm planning to order even more temp guages so I can monitor the delta T in each of our 4 zones & tune each zone in by throttling the ball valves on them a bit. If necessary - they all might be close now.

 

[heaterman]

If..........
.....You have a hot boiler that is cycling and cold pipes you have a circulation problem....as in no circulation at all.
This could be due to the pump or it could be due to an air lock in your zone piping somewhere.
.....
You have a hot boiler that is cycling and hot pipes that get a lot cooler on the return flow,
again, a circulation problem but in this scenario you are getting a very small amount of flow
and again this could be the pump or an air lock..

You have hot supply pipes, a cycling boiler AND hot return pipes that are nearly the same temp as the supply,
You have a problem with heat transmission out in your zones. This can be from dust accumulated on the BOTTOM of the fin tubes, or
furniture that is moved up tight to the baseboard, or curtains blocking air flow etc. The issue being heat is available but the baseboard is not shedding it out in your living space.

All that being said.....
Most residential pumps have a standard 6-1/2" flange to flange spacing regardless of brand or size. Your 111 is a different beast being that it is a coupled pump (separate motor, center bearing assembly and the the impellor and housing assembly).
You should be able to buy an impellor at a plumbing supply house. It's not an item you will find at a big box store. I can get one for you if you have trouble finding one.
That 111 is designed to move a LOT of water at pretty low head (flow resistance). which means the piping around your boiler and the baseboard piping itself should be pretty significant in size. 1-1/4" at least. Even for the zone piping.
If you have normal 3/4" copper fin tube baseboard, I'd have to say that chances are very good the 111 is a totally wrong choice for your system's circulator.

You can see what that series of pump is made to do at the link here... Click on "catalogs" then "in line circulators"

(broken link removed to http://www.taco-hvac.com/en/products/110-120%20Series%20In-Line%20Circulators/products.html?current_category=197#)

I have a couple fairly new ones in my shop that were taken off a boiler replacement job but I don't remember what exact model they were.....seems like 112 maybe....
That style of pump is not used much any more except in large commercial applications. The wet rotor variety has pretty much overtaken anything 50GPM and below.

You would definitely have to change some piping to fir up a pump like the others here are talking about.

 

[Vizsla]

Very strange indeed for that pump. But I unfortunately have seen a particular company drop a B&G PL-36 in place of the factory 007 that came with the little 100kbtu Weil McClain . And on 2 other of his jobs. No it wasn't a special application....

I see he mentioned hearing the water trickle in an earlier post. If it literally was trickling that you heard, I would think air in that section.

Very good post there heaterman for troubleshooting, don't get much easier , just like a troubleshooting tree.

 

[heaterman]

Very strange indeed for that pump. But I unfortunately have seen a particular company drop a B&G PL-36 in place of the factory 007 that came with the little 100kbtu Weil McClain . And on 2 other of his jobs. No it wasn't a special application....

I see he mentioned hearing the water trickle in an earlier post. If it literally was trickling that you heard, I would think air in that section.

Very good post there heaterman for troubleshooting, don't get much easier , just like a troubleshooting tree.

Thank You Sir! Hope it helps this guy out.

 

[salecker]

+1 on love for the Alpha. Absolutely sweet how it ramps itself up & down as zones open & close to maintain constant flow in each zone. An aside is the last power bill we got was the lowest ever for this time of the year. Not by much, but I have to think the Alpha played a small part in that.

I'm planning to order even more temp guages so I can monitor the delta T in each of our 4 zones & tune each zone in by throttling the ball valves on them a bit. If necessary - they all might be close now.

You might want to look into using the ball valves for flow control.I have heard and read that they will erode unless they are completely open.

 

[b33p3r]

Just ran into the same issue. I had air in the lines. Primed the zone using a hose (cool the boiler first) and it was happy again. As Heaterman said the temp difference between the supply and return should tell you alot. My return actually had some good heat to it but the air in the line was keeping it from circulating like it should so I could heat up to 64* but not past it. Another thing I checked after the fact was the pressure in the boiler. My gauge is at 0. No pressure at all. Looks like my auto fill valve is not working. The auto fill valve is preset to 12-14 lbs if I remember correctly and it is responsible for keeping the whole system pressurized. The pressure forces and keeps the air out. Not sure if you have an auto fill but if you do check your pressure gauge. If it's at zero and you drain your zone to purge the air, Remove the nut on the side of the auto fill and you'll find a screen inside. It may be clogged preventing the auto fill from adding water, thus pressure, to the system. If so clean the screen, make sure the needle valve is moving freely and reassemble before priming.
Just something to check while water is drained. I have to redo mine this weekend because I wasn't smart enough to check the auto fill the first time.

 

[maple1]

You might want to look into using the ball valves for flow control.I have heard and read that they will erode unless they are completely open.

I wouldn't throttle with ball valves against a constant speed circ, but wouldn't have qualms doing it against a variable speed constant pressure one, with low flows. I'm doing it right now with my sidearm circ - valve is likely 3/4 closed & flowing 1gpm. Per the digital readout, that is. Maybe it'll eat away at it over time but can't see it doing that much damage.

 

[maple1]

Just ran into the same issue. I had air in the lines. Primed the zone using a hose (cool the boiler first) and it was happy again. As Heaterman said the temp difference between the supply and return should tell you alot. My return actually had some good heat to it but the air in the line was keeping it from circulating like it should so I could heat up to 64* but not past it. Another thing I checked after the fact was the pressure in the boiler. My gauge is at 0. No pressure at all. Looks like my auto fill valve is not working. The auto fill valve is preset to 12-14 lbs if I remember correctly and it is responsible for keeping the whole system pressurized. The pressure forces and keeps the air out. Not sure if you have an auto fill but if you do check your pressure gauge. If it's at zero and you drain your zone to purge the air, Remove the nut on the side of the auto fill and you'll find a screen inside. It may be clogged preventing the auto fill from adding water, thus pressure, to the system. If so clean the screen, make sure the needle valve is moving freely and reassemble before priming.
Just something to check while water is drained. I have to redo mine this weekend because I wasn't smart enough to check the auto fill the first time.

My autofill circuit is valved off all the time. Pressure stays stable. Seems to me if the pressure drops out, it's a sign of a system leak. Leaving the valve closed likely is not a big concern with a big volume of storage attached, but I did it with my old one too after it started acting up once.

 

[b33p3r]

My autofill circuit is valved off all the time. Pressure stays stable. Seems to me if the pressure drops out, it's a sign of a system leak. Leaving the valve closed likely is not a big concern with a big volume of storage attached, but I did it with my old one too after it started acting up once.

Maple1, The air in the lines can be coming from anywhere but no signs of leaks.....yet! The air has been slowly accumulating in the lines. I know this because I first heard a gurgle in my wood boiler a month or so ago and has progressed since then. I did find an air bleeder getting stuck open for a few seconds each time it was tripped so it could be the culprit. Point is as long as auto fill valve is working, the pressure inside the lines keeps the air out. Replaced my auto fill and bad bleeder and my system is happy again.

 

[maple1]

It's likely standard procedure anyway, but make sure you keep a close eye on your pressures (preferably with more than one guage). It's been a long time ago now, but I think when mine went wonky, it got dirt under it or something like that & my pressures went way high & I had water leaking out my PRV. They could also mess up the other way -stick shut or crud up & block flow so pressure won't make up.

When I did my system over last year, I re-used all the fresh fill stuf. But I took it all apart & throughly cleaned it. There was a PILE of crud in all of it.