Low water flow

simba

Hi how much does it cost to fix piping for low water flow issue?

Jamie Hall

Worse -- it might not even be a piping issue.

simba

Thanks both for your quick response. This is laars mini therm jvs 3yrs old. Laars told me it is low water flow issue. When one of the zones calls for heat boiler fires up and starts fine then it makes howling noise and short cycles but when both zones call for heat boiler runs fine and no noise.any help is appreciated

Jamie Hall

That does sound like a low flow issue. That said, we'd kind of need to have some idea as to how the whole system is piped. Photographs? A sketch would be even better.

These things are usually quite manageable.

Zman

Your question about pricing will not be answered here as discussing prices is not allowed.
Those Laars boilers are very finicky about flow. They are copper fin tubes and have very low mass and surface area. They need to be piped correctly to maintain minimum flows.
Can you post pictures of your boiler so we can make suggestions on how flow can be improved without tearing it all apart? A differential bipass valve is often an easy fix.

simba

I tried my best let me know if you need more pic.thanks

simba

How about these

simba

How about these

neilc

can you get one shot showing all of it together?

simba

There is no enough room tp move around.

simba

Laars is telling me again low flow restriction. Any instructions on how to repipe or fix this issue. I will never buy laars product again

Jamie Hall

It's not the Laars product. It's both tempting and satisfying -- but not helpful -- to shoot the messenger.

Any other boiler you might install will have the same problem, only it may not be so kind as to tell you about it before it fails.

I can't tell you how to repipe the system, since I don't have anything like enough information. However, you could look up primary/secondary piping on the Caleffi web site, which has excellent descriptions if detailed, or here in the various library sections. In general the idea is that you have one loop of pipe -- with a pump -- which circulates water only through the boiler and provides adequate flow through the boiler to avoid problems. Then you take off from that with your heating loops with another pump or pumps (depending on whether it's zone valves or zone pumps) which take the hot water they need from the boiler loop and circulate it, according to need, through the heating system, and return it to the boiler loop. Not hard.

HomerJSmith

simba, you tell me it is a low flow issue because someone told you that. I would like to see pics of the whole boiler and piping.

Do you get heat out of both baseboard zones? Is both Honeywell zone valves working?

Sometimes one needs a differential pressure reducing valve, or other bypass, or an ECM pump, or primary-secondary piping .

How long has this been an issue? Is there a valve or other restrictive device in the sys, a closed or partially closed valve? Open your flo-checks, does that help?

What does the temp gauge say the temp is in the boiler when the howling starts?

Low flow in a mini-fin will result in a temp rise to high limit fast and the boiler will then shut off. But you can also get flashing in the heat exchanger which is noisy.

HomerJSmith

Taco pumps have a sealed cartridge in them. Sometimes the cartridge gets fill with debris and won't rotate of rotates slowly. Is your pumps operating efficiently?

There is a manual lever under the Honeywell zone valves. When the valve is energized the lever will move freely from the closed position to the open position. When the valve is not energized and you move the lever from the closed position to the open position, the lever is difficult to move as it is moving against two springs.

Turn both thermostats up all the way and check each zone valve and see if the lever moves freely from the closed position to the open position. If so, the valves are working and the motors are ok. If not replace the powerhead for the inoperative valve. It also may be that the valve isn't getting 24V ac power.

Gman66

https://us.v-cdn.net/5021738/uploads/editor/zu/n9cyznqfsm4t.jpeg

Question for the Wallies: in the first picture there appears to be a boiler bypass (blue handle, fully open). Not sure the reason for this, possibly to bleed off some pressure/flow when both circulators are running? At any rate, I suspect that may be reducing the flow with just one zone calling; can that be fully or partially closed to see if that fixes the problem?

Gman66

@simba : it looks like your thread has lost the interest of the forum already, don't be offended, it happens quite a bit. Lots of interesting problems!! If it were me, I would fire up one zone to reproduce the sound and then, while running, slowly close that blue valve that I copied from your pictures and see if the noise stops. I would leave the valve partially open if the noise goes away with a partial setting and see if any of the smart people on this forum can determine if that bypass/valve is really necessary at all. Let us know what happens!

Jamie Hall

I haven't lost interest, but there seems to be some resistance to repiping so that it's actually fixed...

Gman66

Jamie Hall said:

I haven't lost interest, but there seems to be some resistance to repiping so that it's actually fixed...

Jamie, did you take a look at this picture from the OP?: https://us.v-cdn.net/5021738/uploads/editor/zu/n9cyznqfsm4t.jpeg

There is a bypass between the supply and return that is wide open, any idea what that is for? I believe that would cause the flow to bypass the boiler and thus result in reduced flow through hx. Thoughts?

Jamie Hall

It might, yes. Depends entirely on what pumps are where in the system and which way they are going. That poor thing needs to be piped primary/secondary, whatever that takes.

simba

Guys thank you very much for your help. I am not a plumper just a home owner and not familiar how the piping works. I can’t take good picture because the room is too small to move around. I have two Honeywell zones both work. I do get heat on both zones. The noise starts only when one zone is calling for heat. When both zones call for heat the noise is not there. Pressure is around 18 to 19. The noise starts when the boiler reaches close to it is set temperature at 170 . The blue ball valve if i close it the noise increases and if i open itthe noise decreases. It is just the noise that I cant stand it. Also on the second floor zone sometimes when the thermostat is satisfied it turns off and quickly the zone valve closes and boiler makes quick banging noise and this happens some times not-all the time. So I dont know I am just prying to get through this winter. Again thank you very much for your time and effort

Jamie Hall

Well, you've pinpointed the problem, haven't you? Not enough flow through the boiler when only one zone is calling. And we've given you the solution, so off you go.

As to the banging when a zone shuts off -- that's from the valve closing too quickly. There are many possible causes of that -- and even more solutions. But until the low flow problem is corrected there's no point in addressing that.

simba

Thank you Jamie repiping might be the solution.
.what you think about slantlfin sentry gas boilers are they good. Thank you

Jamie Hall

Slant/Fin boilers are a good make, yes -- one of several. If the installer likes to work with them -- that's what really counts.