Hi,
Just getting settled in my "new" ( to me ) house. A week or so ago the boiler stopped with an error about low flow. The main circulator is a three speed pump that was set to low so I moved it up to high to try and buy some time.
With the pump on high and a call for only hot water the boiler does not error but it cycles rapidly, as in on and off twice in 2min.
I can hear the circulator pump running and it makes a little rattling noise, not good. I tried bleeding the system thinking it could be air lock but it did not make a difference.
When the boiler fires the water temperature gauge moves up until it reaches temp the boiler shuts off then the temperature quickly moves back down again. Here's a video I made of it cycling: https://m.youtube.com/watch?v=a1pQaFgxL2g![image]()
So this has me feeling like maybe the main circulator pump is bad and not flowing enough water. I started poking around to understand the pump that's in there and I'm not sure if I am doing this all correctly:
Here is a diagram of the entire system: https://i.imgur.com/n7bnwU2.pnghttps://i.imgur.com/n7bnwU2.png
Boiler's head loss curve: https://i.imgur.com/kHMvz4z.pnghttps://i.imgur.com/kHMvz4z.png
Hot water tank stats: https://i.imgur.com/fDy2UKa.pnghttps://i.imgur.com/fDy2UKa.png
Circulator pump curve: https://i.imgur.com/R0aiBUp.pnghttps://i.imgur.com/R0aiBUp.png
Seems like I need at least 8GPM for the 1.25" copper and the water tank recommends 8GPM as well.
Water tank literature says at 8GPM there's 6ft of head, if I read the boiler curve right it says at 8GPM is ~7.5ft and there is 10ft of 1.25 copper pipe so that's ~.5ft. of head.
Looking at the current pump's curve I don't see how this could ever have moved 8GPM with a 14ft head.
The piping for this system is different than what I have seen before am I doing something wrong or is this pump just to small?
-G
Just getting settled in my "new" ( to me ) house. A week or so ago the boiler stopped with an error about low flow. The main circulator is a three speed pump that was set to low so I moved it up to high to try and buy some time.
With the pump on high and a call for only hot water the boiler does not error but it cycles rapidly, as in on and off twice in 2min.
I can hear the circulator pump running and it makes a little rattling noise, not good. I tried bleeding the system thinking it could be air lock but it did not make a difference.
When the boiler fires the water temperature gauge moves up until it reaches temp the boiler shuts off then the temperature quickly moves back down again. Here's a video I made of it cycling: https://m.youtube.com/watch?v=a1pQaFgxL2g

So this has me feeling like maybe the main circulator pump is bad and not flowing enough water. I started poking around to understand the pump that's in there and I'm not sure if I am doing this all correctly:
Here is a diagram of the entire system: https://i.imgur.com/n7bnwU2.pnghttps://i.imgur.com/n7bnwU2.png
Boiler's head loss curve: https://i.imgur.com/kHMvz4z.pnghttps://i.imgur.com/kHMvz4z.png
Hot water tank stats: https://i.imgur.com/fDy2UKa.pnghttps://i.imgur.com/fDy2UKa.png
Circulator pump curve: https://i.imgur.com/R0aiBUp.pnghttps://i.imgur.com/R0aiBUp.png
Seems like I need at least 8GPM for the 1.25" copper and the water tank recommends 8GPM as well.
Water tank literature says at 8GPM there's 6ft of head, if I read the boiler curve right it says at 8GPM is ~7.5ft and there is 10ft of 1.25 copper pipe so that's ~.5ft. of head.
Looking at the current pump's curve I don't see how this could ever have moved 8GPM with a 14ft head.
The piping for this system is different than what I have seen before am I doing something wrong or is this pump just to small?
-G