Heating Help

Cirualation pump

We have two 225,000 but boilers at our church.
Each boiler has a small taco pump on the side that the contractor did not wire up but they are piped up.
The boilers feed  three bell and gossett pumps each for a different zone.
I question why they would not have used them (tacos), I think they are suppose to help move the heated water through the boiler.

I also question the piping arrangement. Would any one have a proper piping diagram?

manual

The manual for those particular boilers will have examples of proper piping for them. Which manufacturer and which model?

Cirualation pumps

The boilers are Dunkirk
PVWO-BD
245,000 BTU

Picture

A picture would help

Picture

I will get a pictures soon. Thank you

Photos

Pictures of two dunkirk boilers installed in 1998

Circulation pumps unused:

It seems to me that the original installer was trying to get balanced and even flow through the two boilers. Its hard to see but it looks like the take-offs too and from the system is about exactly in the middle of the developed piping. I would think that they should be wired to run together so that they ran when any or all of the system circulators were to run.
Is there a control to stage the boilers? To make one or both run on demand?
It seems to me that the Mark Etherton rule could come to play. About his lazy brother in law going around in circles. It would be nice to research the reason for not connecting the boiler circulators or what happens if you connect them up.

Primary / secondary

From the sounds of it, the boilers were piped in primary/ secondary.

The pumps on the boilers themselves are there to provide enough flow through the boilers without causing trouble for the boilers.

This way regardless of how many of the zones are calling, and when the boilers will get consistent flow.

This arrangement will also limit the standby heat loss of a boiler that is sitting idle.


Wait, I guess I'm confused. Are they in the middle of installing the boilers? Or has this been this way for a while?

reply,

The boilers were installed in 1998 and at that time the contractor disconnected the power to the taco pumps on the side of each boiler. The system does have three bell and gossett series 100 hv pumps. 
Also do you think chemically cleaning the boilers is worth it?

Thank you for reviewing  this question.

disregard

circulators

Those are the pumps supplied with the boilers, and why he would leave them in the system and not use them is a mystery. Is there a specific problem you are having?

Cirualation pump

I am not sure why they were never connected. The boiler on the right has become noisy and it seems to take along time to raise the temperate in the sanctuary.

They should be connected.

It looks like you have a primary secondary setup although it is hard to see the connections. Could you get a pic from the side? It might also help to draw a 2 dimensional piping sketch. I don't see any check valves. I would expect to see one on each boiler and one on each zone. They will be little cast blocks in the pipes with arrows on them. What is controlling this thing? Do both boilers just fire up and run with every heat call. I think the thing has just been working from the ghost flow of the zone pumps. 

I love the.....

Hoffman 75 steam vent on the air scoop..... the expansion tank should be connected there instead. There should be no automatic air vents on the system when using a conventional expansion tank. There definitely should be a boiler staging control w/ multiple boilers....otherwise you might as well just use 1 boiler. Time for a re pipe..... in the spring.

boiler pumps

If you look closely at the pictures you will see that the boilers are NOT piped primary / secondary. Those boiler pumps should not have been installed. They will induce flow in all of the zones if they are wired to run. ( all zones will get heat at the same time even if the zone pump is not running) Those pumps are causing blockage to flow and should be removed. The impellars have small passages and may be blocked with debris. And yes the compression tank has to be repiped to the RED inline air seperator. ( remove the auto air vent ) Staging the boilers will help with efficiency but would work better if the boilers were piped Primary / Secondary and utilized those boiler pumps.

Pumps

From the look of it (and I can't see where the tee goes) both pumps are pulling back from the return.  Now for a logical reason.......I can't think of one.  I suspect that they might have been installed originally and then the system was modified and the B&G's were installed to either zone or get better flow through the system and they just left the other circs in place.  At the very least you could take them out but if it were me I would gut the room and re-pipe the whole mess while you are at it,  I love the Hoffman steam vent on the air scoop also,  Classic

Thank You !

To everyone, thank you for your suggestions. I greatly appreciate them. I will post a few more photos as soon as I can.