Plumbing Question - Heater Bypass

[garywi]

Hi Guys, I was re-plumbing my heater. As I was curious , I shut off the valve labeled Heater Bypass. I turned on the pump and water still flowed through the plumbing at the heater. I got a gusher right in the chest.

Am I missing something. What is the valve supposed to do...

Thanks

 

[mas985]

The bypass may not prevent water going through the heater but just bypass some around it. But where did the gusher occur? That should not happen.

 

[garywi]

Hi Mark, while I had the "out" plumbing off the heater, I ran the pump with the heater bypass valve closed and water still gushed out of the "out" pipe at heater. Also, I don't understand, at the filter, there is a union so water coming out of the filter travels in two directions.

 

[mas985]

Hi Mark, while I had the "out" plumbing off the heater, I ran the pump with the heater bypass valve closed and water still gushed out of the "out" pipe at heater.

Ok, that makes sense. I think it is operating as intended. It is not for heater isolation but simply to reduce head loss.

Also, I don't understand, at the filter, there is a union so water coming out of the filter travels in two directions.

Again, that is for the heater bypass. One direction goes into the heater and the other ties in past the heater.

 

[garywi]

Thanks Mark! Ok, still, what is the purpose of this valve, heater bypass.

 

[garywi]

I ask because I am still learning about flow and hydraulics. My heater is currently hitting the high limit temp and shutting off. Wondering if this valve setting has anything to do with it...

 

[garywi]

Solved heater high limit error. Turning heater bypass valve half way closed, which I assume directly more water through the heater. I fixed my flow problem. Yea!

 

[mas985]

Thanks Mark! Ok, still, what is the purpose of this valve, heater bypass.

Some heaters require a bypass if flow rates are too high because they don't have a built in bypass. But most modern heaters have built-in bypasses.

If the filter pressure does not change much, you might just leave that valve closed. Too little water through the heater could stress the heat exchanger over time. But check the heater manual to see if it requires a bypass.

 

[garywi]

Thanks Mark. I checked and my Laars has an internal bypass, but I never understood the external manual bypass valve until today. I am thrilled to understand now, why my heater was overheating and thrilled I don't need any repairs. I wish the manual had this simple step in the troubleshooting guide.

 

[garywi]

testing signature