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DHW Demand

casper1290casper1290 Posts: 4Member
Hi guys.. I have a Burnham boiler and indirect how water heater.. everything was fine until I replaced the two gaskets on the pipe that crosses from the return to supply ports. Now, my DHW demand is constantly on. The return pump runs constantly now. Not sure what I could have messed up. The thermostat on the water heater must work since the valve from the boiler opens and shuts as I adjust the temp... the only thing I know I hit while changing the gaskets was the sensor on top of the return piping that connects to the VS3000... Thoughts?





Comments

  • mikeg2015mikeg2015 Posts: 760Member
    This isn’t a steam boiler, so wrong section.

    FOr troubleshooting you need to work backwards from the device that calls for DHW. Should be on the indirect tank. Remove wires to see if it stops. Could be a short. Maybe aquastat has gone bad. IF it doesn’t stop then trace the wires. THere a chance a relay or contractor if stuck on zone panel.
  • HVACNUTHVACNUT Posts: 2,030Member
    edited May 15
    If you didn't disturb any of the wiring, then it could be wires got pinched and shorted somewhere or water damage to a relay or other controls.
    The Tekmar is showing circulator operation w/o a demand and the circulator is showing a demand. Shut off the power and work your way back starting from the circulator.
    A pic of the wiring diagram might help.
  • ZmanZman Posts: 4,807Member
    Your tekmar is set so the boiler puts out 150 degree water during DHW call. Your DHW tank is set to 145 degrees. Those 2 need to be farther apart or it will never make temp in the tank.
    Either turn up the tekmar setting up (180 or so) or turn down the tank aquastat and see if that solves it. I bet the supply sensor was loose and giving a false low number before you bumped it.

    In other news, what model boiler it? Is it a condensing boiler? Who attached the clear tubing? Why 2 pumps in series?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • casper1290casper1290 Posts: 4Member
    Well, testing 1 part at a time, the culprit ended up being the valve in the 2nd picture. I wired in a new one and it worked properly.. now I'm just waiting on Erie quick connects to put the new one in.

    As far as the questions Zman, it's a Butnham RV7NSL. I know barely anything about boilers... so idk of its a condensing one.. clear tubing? On the floor? All of this was installed before we lived here (1.5 yrs) 2 pumps.. one on supply main and one on return main... not how it should be?
  • mikeg2015mikeg2015 Posts: 760Member
    Zman said:

    Your tekmar is set so the boiler puts out 150 degree water during DHW call. Your DHW tank is set to 145 degrees. Those 2 need to be farther apart or it will never make temp in the tank.
    Either turn up the tekmar setting up (180 or so) or turn down the tank aquastat and see if that solves it. I bet the supply sensor was loose and giving a false low number before you bumped it.

    In other news, what model boiler it? Is it a condensing boiler? Who attached the clear tubing? Why 2 pumps in series?

    That model boiler has an inducer so you can vent using smaller SS pipe without a chimney, including horizontal vents options. But it still requires pitch like condensing boiler and condensate drains since it’s not double wall and has no secondary air.

    Other advantage is there is usually the option of an direct vent intake kit for combustion air as well.

    Clear PVC tube it’s OK. But I’d rather see 3/4” PVC pipe
  • ZmanZman Posts: 4,807Member
    The boiler is condensing so your lower temps are good.
    Aside from the stains in the cabinet and sloppy workmanship, the condensate drain is OK.
    Having 2 different model pumps in series is odd. What type of system is this? Radiant or baseboard?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • HVACNUTHVACNUT Posts: 2,030Member
    Explain your diagnosis again. It seems like a bad end switch in the zone valve. Contacts 3 and 4 are closed on the Tekmar so it thinks theres a DHW demand.
    What do you mean by quick connects? Do you mean the actuator?
  • casper1290casper1290 Posts: 4Member
    HVACNUT - This is how I understand my setup.. Thermostat on Water Heater Triggers Erie valve motor on water heater circuit
    to open. The sensor on the valve reads open/closed and tells the Tekmar that there is/isn't demand.. which then turns the boiler and/or pump on/off as needed. I'm thinking the sensor in the Erie valve was stuck in the ON position, telling the Tekmar that the valve was constantly open, since when disconnecting the sensor line the Tekmar shut the circuit down. The "quick connects" that I ordered from Erie are pictured in the following picture.
  • casper1290casper1290 Posts: 4Member
    The connectors allow me to solder them in place once and replace the valve as needed.
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