Primary boiler pumps working or not?

SweatyInToronto

This is weird. Our boilers were just cleaned, the HX was cleaned on both. Also, we started to change the volute portion of an S45 circulator, however we lost perhaps 5-8 gallons of water because one of the primary loop shutoff valves wasn't closing completely. So that was put on hold. However, what's happened since is that

a) One of the boilers is popping and tinging when it's turned on.
b) The other boiler that wasn't seemed to go to a temp I wouldn't expect for mild weather, like 170. The min is 140.

The 2 boiler S25 circulators seem very quiet and one tech who didn't want to play with the system because another had started, thought they aren't on at all. They are both very quiet and only seem to vibrate when the S45 is on. Also he looked inside and didn't see any turning (not sure you would).

Both primary S25 boiler pumps are wired to on constantly rather than just on when the boiler is firing.

The system pressure is 22 pounds for a 3 floor building with a basement, so that seems enough.

I've shut off as I don't want to damage a boiler if there isn't enough fluid in the system.
My first thoughts would be an electrical connection, a valve left shut or sensor damaged, or possibly not enough water in the system? Just shots in the dark really. Are there fuses for these pumps?

What would you think is the most likely cause and approach to tackle this?

Thanks so much! Will be shivering and no longer sweaty in Toronto if this one lasts very long!

hot_rod

sounds like no or low flow. Circulator airlocked?

SweatyInToronto

So in other words Bob, are you suggesting that when water drained out, not enough was left in the primary loop for there to be meaningful circulation? If so there wouldn't be enough water to connect with the radiator circulation loop to push air out and around the system, and for water to replace the losses is that about right? So we're choking on air?

We do have an auto fill setup and a pressure relief valve, so I'd imagine that if water pressure were really low it would shoot some in there. Would pressure be low if the water level is low necessarily? It reads 22 which seem sok.

Also I'm not clear if the boiler pumps are rotating or not. It doesn't even seem that they are on, but it might be that they are just really really quiet when they aren't circulating water. Is there direct way to tell if the impeller is rotating?

I guess we can manually inject water into the primary loop and see what happens! Is this what you would suggest?

Thanks much,

Larry

Jamie Hall

If the water was drained out and there was no deliberate -- and thorough -- attempt to purge the air on refilling, yes indeed there could be insufficient water for any circulation to take place. One can pressurize trapped air just as well as water, after all.

SweatyInToronto

Thanks Jamie. Typically when there's filling, would it be injected in to the primary boiler loop? I think that's where it goes but I'd have to check tomorrow. I'm not sure there was an attempt to manually replace the lost water. How would air be bled from this loop?

By the way I purchased "How Come?" by Dan Holohan as it seems to start with the basics. Are there other books that you guys would recommend to start with? Haven't read a book in years, this one really primed my reading pump!

Also, if we put in an air eliminator would it go into the primary boiler loop or the secondary radiator loop and why? I believe Dan states the primary boiler loop, but I'm not clear why. Would the air, dissolved or otherwise, that's in the secondary radiator loop necessarily end up there?

Jamie Hall

If the system was really drained, there will be -- or have been -- air in all of the piping and, most likely, most of the boiler. To get that air out, you need to bring the system up to pressure and then actively purge it -- loop by loop -- with the purge water going out of a drain somewhere. If there are drains/vents on the radiators, they need to be opened to let the air out, all the while keeping pressure on the system. There's no other way to refill a drained system. You can't just simply run it and hope.

The air separator would go on the primary loop. Look in Dan's book for "pumping away" for more thoughts on what goes where -- and why. All of the water would eventually get there, but it would take awhile -- but only once the system is properly purged of air. Until its purged you'll likely have poor or no circulation in parts or all of the system.

SweatyInToronto

So just to clarify Jamie about 8, 10 gallons  came out from the primary loop (it seems) when removing a pump because a shutoff valve didn't close. Was attempting to replace the volute side of an s45 at that time. Understand a full drain and fill would be a much larger undertaking. 

In terms of the air eliminator seems like the better ones can remove microbubbles. So it should go right before the circulation pump? 
I'll have to pick up "pumping away" for sure! The forward speaks of piping to avoid bleeding. Not sure if it's using an eliminator but that's a goal, preferably without a lot of re piping ! 

EBEBRATT-Ed

put an amprobe on the pump wire that will tell you if it is running

mattmia2

Boiler could be shut down because of the low water cutout if it is controlling the pump too. What model boiler is it?

The no bleeding refers to installing purge valves to force the air out with fresh fill water. Your system may or may not have valve that can be used to purge.

SweatyInToronto

Boiler actually didn't shut up off, just was pinging, tingling, popping... Not violently. So I shut it down in case it was dangerous. 

Will check it today with techand provide further info. 

Purge valves eh?  Read about those. Slick. 
Pricy items? 

mattmia2

SweatyInToronto said:

;

Purge valves eh?  Read about those. Slick. 
Pricy items? 

They are just valves.. it is knowing where to put them and how to use them that is the hard part. You may already have valves that can control the flow such that you can purge through them.

SweatyInToronto

The am probe will check for current but not necessarily say rotor and impeller are turning correct?

Here's the unit... 2 of these. I was told piped together in a primarp loop but will confirm this today. 

hot_rod

I'd bet you just need a good power purge, flow through every zone and pipe at at least 20 psi.It takes a series or some well placed purge valves to accomplish that.
Rare that you can drain water from a hydronic system, refill and expect it to be air free without some sort of purge.


The air sep always goes at the hottest point in the system, ideally close to boiler out, for best performance anyway.

Primary secondary can be confusing, and the boiler may or may not be in, or, the primary loop.

The primary loop according to Gil and his disciples is the loop that has the expansion tank connected to it, hence the PONPC is in the primary loop.

SweatyInToronto

I've learned a lot in the past 24 hours.

Firstly, the pumps weren't pumping at all, because there was no current reaching them. Crazy. It just happened suddenly and coincidently with the water loss, so air seemed more likely the cause. The em meter showed no current though.

An electrician tracked it down . It seems that a high limit sensor failed, which cut power to the pumps. It's an old sensor from the oil burners, so he put a bridge across it. We have high limit on the boilers themselves, as well as the Tekmar, so it's no longer needed as a cutoff. And the pumps they are pumping again, which is a relief. Whew!

As far as future work goes, setting up purge vales to allow most of the the air to come out without bleeding and the air eliminator sounds great. Will be reading pumping away. Probably this will have to wait until summer now as it's too close to heating season.

I'd have to understand a bit or a lot more regarding the placement of the air eliminator. I did well in physics in high school but this seems like half thermodynamics and half Rube Goldberg (no insult to Rube intended.) Seriously, I like it! It's probably just that our system went through 80 years of revisions without documentation or any one left who can explain it!

Our tech believes its best to have the Air eliminator on the "secondary loop" before (upstream) of the circulation pump. Our circulation pump is on the return before the boilers. The expansion tank is in the ceiling and I think is on the return side - but have to look again. Will sort it out. Not in a hurry.

In the short term, I'd like to get the boiler pumps to cycle on and off along with the call for heat. At least that will save some electric and reduce the chimney effect, which makes sense.
Baby steps.

Thanks for your support.

SweatyInToronto

Am sure it could benefit from many things, power purge among them. Though it's only a 1 zone system...

Bottom line on the problem, it was current issue. A high limit cutoff of some sort went belly up and cut the power to the boiler pumps. The electrician bridged that and the motors kicked up.
There are other high limit cutoffs in the boiler itself and the tekmar 261 so that must have been a vestige of a prior system.

Thanks much for your insights. Will keep learning!

EBEBRATT-Ed

@SweatyInToronto

I would be cautious about bypassing safetys

SweatyInToronto

Fair enough. Bypassed for now. Shoulder season. It's the third failsafe so it one had to go,... 

hot_rod

Popping and tinging are not usually good sounds to hear from a boiler, and can often lead to over-heating, hense the safeties pop.

A simple test is one hand on the supply out of the boiler, the other on the return pipe. As soon as the burner lights off you should start feeling a temperature difference.

if not the boiler is at risk, and you may not get heat to the zone either.

mattmia2

an electrician isn't the one to determine if a limit switch can be bypassed.

SweatyInToronto

The way this was wired even if it shut off the pumps, the boilers could still fire. So it was  worse than nothing maybe. 

One baby step to take is to start and stop pumps when boiler turns on and off, and also to prevent boiler from Firing unless its pump is running, no? 

The boilers lasted 15 years as is, but 
I believe the tekmar 261 supports this.... it was never set up. Our circulation pump runs constantly, which I've read is appropriate with outdoor reset, though I'm not sure the rationale for this.  

mattmia2

If the boiler is set up as warm start, the boiler could be set up to maintain temp even if there is no heat call. High mass boilers don't require circulation while firing the way a mod con does.