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tankless combination boiler

slocumrd2003
slocumrd2003 Member, Email Confirmation Posts: 7
edited September 2021 in THE MAIN WALL
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 insite.

Comments

  • Ironman
    Ironman Member Posts: 7,555
    What is the ODR curve set to? Also, the WWSD setting?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • slocumrd2003
    slocumrd2003 Member, Email Confirmation Posts: 7
    i don't have the outdoor temp sensor hooked up currently and have the setting off for that sensor. would this effect this?
  • slocumrd2003
    slocumrd2003 Member, Email Confirmation Posts: 7
    also it appears i have posted this under job opportunities?? whoops. can't seem to move it
  • Ironman
    Ironman Member Posts: 7,555
    edited September 2021
    Most boilers will give you an error code but allow the burner to fire if the sensor is not connected. You’ll have to consult the I/O manual for that.
    I’d check the SWT setting to see if that’s set too low.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • slocumrd2003
    slocumrd2003 Member, Email Confirmation Posts: 7
    i will plug it in and put it outside just to eliminate that as an issue but that sensor only changes the water temp setpoint based on outside temps. I have the water temp setpoint at 150°F and the return temps never get past 110°F before it stops heating and turns pump off. I can't wrap my head around why the heater will stop doing anything if the thermostat and valve are calling for heat.
  • Ironman
    Ironman Member Posts: 7,555
    SWT setting, proper flow through boiler (might be air bound), flue and vent not blocked, drain not blocked, etc.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,495
    Is this a new install or has it been in service for a while? Just going to have to go through the boiler manual and figure it out
  • slocumrd2003
    slocumrd2003 Member, Email Confirmation Posts: 7
    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 150°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.
  • slocumrd2003
    slocumrd2003 Member, Email Confirmation Posts: 7
    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.
  • Ironman
    Ironman Member Posts: 7,555
    Most manifolds are similar to each other, but you should consult the manufacturer’s manual.
    I’ve e never seen a Sharkbite manifold, but I think SupplyHouse.com has them and the manual on their site.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • slocumrd2003
    slocumrd2003 Member, Email Confirmation Posts: 7
    I looked at the manual. it has a feature list and installation instructions, but no usage instructions. Nothing explaining purging, adjusting, how to manage flow, etc. This was the info I'm keen on. But if it operates like the others you can adjust the "regulation ferrule" at the bottom of the flow tube. which I wasn't aware of. hopefully this is my issue
  • GroundUp
    GroundUp Member Posts: 2,124
    You most likely have airlocks in 2 of the 4 loops. Very common issue with DIYers. You need to purge each loop individually with some pressure (whether domestic water or pumped) to push the air out of the loops.
    Ironman
  • epmiller
    epmiller Member Posts: 28
    I agree with GroundUp above. I use a small pump (most often used to empty a dead water heater) to recirculate water out of a 5 gallon bucket and into the manifold and do one loop at a time. Return the water from the manifold back into said bucket below the water level and you see the air you are pushing out. When that stops let it run a bit for insurance and start the next loop. Always has worked for me.

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