# combination boiler heat demand issues



## slocumrd2003 (Sep 29, 2021)

subject: Rheem Prestige 9.9 GPM Natural Gas High Efficiency Combi Boiler

So I'm having an issue and don't know what is going on. My basic understanding is when the thermostat calls for heat is send the signal to the zone valve. when the zone valve fully opens it closes the switch. when the boiler sees the switch close it know it needs to heat. so in theory the boiler should turn on the pump and start generating the heat per the settings. the problem i have is it stops after some time even though the zone valve is still open/thermostat still calling for heat. so essentially my house isn't heating up to setpoint because the boiler is for some reason not staying on until the thermostat is satisfied. I'm at a loss here and could really use some insight. 

Outside sensor isn't connected at this time if that helps


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## Logtec (Jun 3, 2018)

Call a lic’ed professional


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## skoronesa (Oct 27, 2015)

Logtec said:


> Call a lic’ed professional


Call them what? Pretty?


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## Logtec (Jun 3, 2018)

skoronesa said:


> Call them what? Pretty?


sexy, pretty, husky, sturdy… 
what ever gets the problem fixed.


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## slocumrd2003 (Sep 29, 2021)

It is a new install. After going through the manual again I've sorted out the boiler part. It cycles between 120°F and setpoint of 180°F. Only firing the burner when reaching low setpoint. So I understand that part now. The issue with not heating the house properly is 2 out of 4 loops are not flowing. They are all around 270 foot 1/2" pex-al-pex loops and I can't find any pinches. Moved one loop to another output on the manifold and still nothing. Need to look into how to resolve this issue.


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## slocumrd2003 (Sep 29, 2021)

after doing some research on my sharkbite manifold (no info on how to use) I stumbled across a video on a different manifold. so there is a flow knob that is adjustable on the return manifold. and there are flow tubes on the supply manifold. do the flow tubes also adjust? the video showed both able to turn and i didn't know that was a thing. i will check when i get home but this may be my issue.


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## OpenSights (Mar 23, 2015)

slocumrd2003 said:


> after doing some research on my sharkbite manifold (no info on how to use) I stumbled across a video on a different manifold. so there is a flow knob that is adjustable on the return manifold. and there are flow tubes on the supply manifold. do the flow tubes also adjust? the video showed both able to turn and i didn't know that was a thing. i will check when i get home but this may be my issue.


You haven’t posted a proper intro.








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## slocumrd2003 (Sep 29, 2021)

ok, in my haste I didn't realize this is for professional Plumbers only. My bad, i'll search elsewhere. Thanks for the comments


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