Need base board heating advice - 1 zone is down

Status
Not open for further replies.
Joined
Sep 23, 2015
Messages
4,438
Location
Connecticut
Changed out a failed Taco 007IFC circulator pump today as the old one would no longer pump. I had been trying to get a certain heating/plumbing guy to show up and help me as well as doing an annual boiler clean and tune up. He took the job in April....and I finally tossed in the towel 2 weeks ago after 4 months and 4 phone calls to get him to show up. He just stopped calling me back. He even said he already had the pump but had started another job. As a minimum he could have just called back and said he was too busy and wouldn't be able to do it.

Ordered the pump myself and installed it today. Seemed to be pretty straight forward - identical flanged bolt in - exact same pump and orientation. I have no isolation valves for the Burnham boiler so you have to drain 90% of the 11-13 gallon system. Initial testing went perfectly. The bathroom/bedroom zone heated up to 190 deg F. The living room/kitchen zone got plenty hot too. I could feel the heat as I bled the 7 high point vents of air....then closed them (3 on one side, 4 on the other). That was the first cycle. When I ran a second cycle of heat the living room/kitchen zone may have not been as hot. Not really sure. But, on the 3rd cycle, no doubt that zone was not heating properly while the other zone was fully hot. I could wrap my hand around the living room and kitchen pipes and hold them there. Somehow, there's a blockage to flow in that one zone. I bled off the vents on those 2nd and 3rd cycles. Just got warm water at best on the cool zone....sputtering air and hot water in the other.

So what could have changed? And what's stopping flow in half the system? I also note that the Taco 007IFC pump motor sounds a bit noisy. The motor casing gets quite hot that you can't keep your hand on it....reminds me of how hot the old motor got before it fried. When checking into some specs I believe I found that the motor casing is rated up to around 240 deg F...though running at 140-180 deg F would make more sense to me. I never recall hearing the gurgling noise when running it before. The last one ran for 9 years. Is it cavitation or just normal flow noise? The system hasn't been run since late April so my memory is faded. The last time the system was opened and drain was in 2008 when a new boiler was installed. It's never been drained since. I don't recall the burner techs having any issues getting both zones to come up quickly.

My only other thought is the 2nd baseboard heater in the living room. I think that was added on by the homeowner 30-40 yrs ago when they modified that portion of the living room. For one, that 7 foot baseboard (copper pipe with aluminum fins attached) has NO high point vents on the outer elbows. Those then drop down into the basement to join the rest of the zone header. I poked around and found a tiny plug drain on the "bottom" downstream elbow. What good is that? You don't need a drain there. And that's useless for a vent. I tried to unscrew the plug just "because" as there was nothing else for me to do but call a plumber/heating tech. It wasn't budging and started to strip. It's 3/16" max and sits right above the foundation behind the electrical breaker panel of all places. What idiot installed this?

Despite not having a vent on that one base board section, the house heating has never been an issue. Not once in the 26 years I've been here. And I do recall going through the vents once or twice in years past. Very odd too that I had partial heat on that side on the first startup. Could the additional running have caused an air pocket to build up that finally stalled the flow completely after a few cycles? Could something have come loose in the system (from the pump?) and made its way down stream to the living room zone? An air bubble seems the most logical thought. It may be that I need to drill a hole for a vent fitting on that 7 ft base board. May need that plumber after all.

It was looking pretty good for a while there today. I was already to wrap the job up when I went back one last time to check all vents and piping temps when I found that one side was cooler than earlier. The one circulator pump flows to both zones. It's about as simple as it gets. There are a pair of inlet isolation stop valves to each zone (so you can save energy if you want and isolate a zone). They do work and both are open. I've never used them except to cycle them every few years.

Any other thoughts? Thanks.
 
Properly set up, one should never have to go around the house venting air. It should crank all the air bubbles down to the basement then separate them in a central air separator. Of course these systems are never properly set up.

You have noise from the circulator and no flow, the pump may be air bound. I would try cracking the flange on the pump. Do this with the circulators running but the boiler shut down so the water is not dangerously hot.
 
Originally Posted By: mk378
Properly set up, one should never have to go around the house venting air. It should crank all the air bubbles down to the basement then separate them in a central air separator. Of course these systems are never properly set up.

You have noise from the circulator and no flow, the pump may be air bound. I would try cracking the flange on the pump. Do this with the circulators running but the boiler shut down so the water is not dangerously hot.


Once the system was nearly full, I shut each vent once water flowed out. And the system immediately heating rapidly and properly...only the first 5-10 minute cycle though.

I do have an air separator (Taco air scoop with a vent canister on top). That was bleeding air fine during the first half of the cold fill. I definitely have flow from the pump because the bedroom heating zone is getting very hot and heating that part of the house. My wife ended up opening the windows to get rid of the excess heat. The supply lines are very hot as well as the return lines leading to the boiler. Yet, at the same time the other zone return only 5 ft from the boiler is cool or barely above ambient.

Could over-tightening the circulator pump flanges cause any issues? This circ pump has an internal flow check installed at the outlet or supply side from the boiler...a duplicate set up of my old pump. Same orientation pointing down on the return side to the boiler. Not the optimum set up per Taco (who likes them on the outlet). I've had the same setup for 26 years w/o any issues. During the cold fill, I could hear that 6 ft - 1" line for the pump piping stab filling up. With the vertical orientation, how would air get trapped in the pump cavity?
 
You keep saying "zones" but it sounds like there is no independent zoned temperature control, just one thermostat for the whole house, right?
 
Originally Posted By: mk378
You keep saying "zones" but it sounds like there is no independent zoned temperature control, just one thermostat for the whole house, right?


Yes. 2 separate piping runs for a single circulator, and single thermostat. The 2nd piping run is not flowing...even though it flowed adequately the first time out today. Which seems to point to an air pocket hanging up in the one of the 4 radiators on that side. Those are an initial 20 foot run with a vent, then a dip and rise to the 7 ft baseboard w/o a vent, then a dip and rise into the kitchen multi-tubed/finned radiator, then down into the basement to an old style cast iron radiator from the 1930's-1960's. Then flows back to the boiler.
 
More appropriate to say there are two "loops" then, which are teed together in the boiler room.

You said that there is a manual valve in each loop. What happens if you close the one on the loop that does flow, forcing everything to go through the other one?
 
The pump is cavitating and is air bound. That is why it is warm to the touch. My system is hot air but I have some general pump knowledge from dealing with a pump.
 
Last edited:
Originally Posted By: mk378
More appropriate to say there are two "loops" then, which are teed together in the boiler room.

You said that there is a manual valve in each loop. What happens if you close the one on the loop that does flow, forcing everything to go through the other one?


Not a bad idea MK378. That might force more pressure and flow (less head) to that one side, better chance of pushing out a bubble if it's there. Didn't try that...but will in the morning after my aching back feels better. The only reservation with those valves is that they're 57 years old with crusty green patina. I cycled them earlier in the week in the event I thought of isolating part of the system from draining out. Immediately got a pair of packing leaks. And was lucky there was enough packing nut movement left to stop the drips. A good mechanic would have repacked them by now. But they're probably OK to cycle another time.
 
Originally Posted By: andyd
The pump is cavitating and is air bound. That is why it is warm to the touch. My system is hot air but I have some general pump knowledge from dealing with a pump.


I can buy that. Is the air coming from that "cool" piping run with potential air in it?

Which pump flange(s) to crack to bleed any air? In hindsight, maybe I should have left the flanges less than fully tight when filling that pipe section, to ensure all air came out? Since the circulator runs for a minute before the burner starts on a heating cycle, that would be a safe time to crack flanges.
 
Turn off the fuel source and run it cold if you're going to be cracking open pipes. 180 degree water is nothing to trifle with.

The general topology should be

Boiler --> air separator --> circulator --> heating loops --> boiler

The pressure tank and fill valve should be teed into the system in between the air separator and the circulator. This is the so called "Point of No Pressure Change", you're guaranteed to have 15 psi of mostly water there to reduce the chance of pump cavitation.

Putting the pump on the return side of the radiator loop(s) is decidedly wrong. It has to deal with all the air that may come out of the radiators.
 
With the system properly cold filled and vented through each radiator, there should be very little air left in the system. And that was the case on my first heating cycle today. It does bother me that the 7 ft base board radiator has no high vents. When I was researching my failed circulator pump a few months back, the Taco drawings did allow for their circulators being on the return piping, even if not ideal. I understand what you're saying about venting downstream away from the boiler components.
 
Good advice MK378. Shutting the opposite loop iso valve did the trick!

Warm water flowed instantly through that cold circuit, right up to 180-190 deg F. Plenty of gurgling and the sounds of running water in the basement piping (or was it minor water hammer?) as things heated up. Then opened up the other loop and both sides ran together hot.

Circulator motor casing is in the range of 180-190 deg (or a bit higher?) as it's too hot to touch just like the heating loops. It could be normal. Once the burner kicks off at the high temp, the circulator runs on its own for a bit, and it still sort of gurgles. Will want to get that verified by a burner guy. I never paid attention to the motor temps on my circulator pumps until April when I noticed the burner wasn't heating the house on command. It was then I questioned the circulator pump and noted the casing temps got real hot within a few minutes of being turned on...and it certainly wasn't flowing any water as the downstream piping wasn't getting hot. This time it's flowing hot water through both loops. With the burner on, you can't hear any noises from the circulator as they would be drowned out. I'll check those flanges tomorrow.
 
It's air in the pipes any way you look at it. You said you got sputtering air and water on the last bleed, so I'd start there. Bleed from the lowest to the highest until you get a solid stream of water.
 
In a simple single zone installation like yours, the circulator should run all the time the thermostat upstairs is calling for heat. The burner should fire until the boiler reaches 180, then cycle on and off as needed to keep it hot. When the house thermostat is satisfied, the burner and circulator both just stop.
 
System ran much better this morning after running a hose from the ceiling drain valves to outside. Tried to vent one loop at a time while the other was semi-isolated. Can't say I saw much air being vented. Did this to both loops. The 3/4" Thrift Peru Ind purge/vent valves are puzzling to me. As I suspect the screw driver fitting on the side of the valve is probably supposed to be a stop valve. I could turn those screws a dozen times or more in each direction. They don't seem to be functional - other than to drain the system. Would be nice to have a second set of ball valves in the return to the burner to properly separate a loop for a higher flow venting.

Can't really say what I did but the pump is no longer gurgling/cavitating. It runs pretty smooth though the casing is still at 180-190 deg (motor rated for 240 deg F). Ironically, on the first heating cycle attempt, the loop that was never giving me any problems started to resist flow and stay cooler. Cycling the 2 loop supply iso valves and venting radiators brought it back.
 
Last edited:
Once flow is established, the air separator (if properly installed) should be taking care of any residual air. Have you ever heard air coming out of the air separator? Its automatic vent valve may be stuck, try banging on it.
 
I heard the air separator venting heavily during the initial cold fill yesterday. Sounded like a dull roar. So should still be working. Have not heard it since. Will give it a tap.
 
Status
Not open for further replies.
Back
Top