Big Al House
New Member
Hello - new to forum and have been reading some posts - hoping for some help here in Eastern Mass. where we are expecting snow (again). This Navien 240 supplies DHW to us via a 30-gallon holding tank and heats three zones on a Taco relay. All three zones have a Honeywell set-back wired thermostat.
We had no heat this morning as the Navien displayed a low water pressure code. I noticed a small drip in a copper pipe connected to an air vent which must have caused the low pressure, called in a plumber who fixed it and the unit subsequently fired up. Indeed, hot water went through the PEX pipe and we thought all was well, so he left. A few hours later, noticed house was not getting any warmer and it seems the Navien supply temp never went higher than 134 degrees. (It normally reads "P 26.8 and S 168" as the remote is set to 170 degrees.)
I've read that the Navien will always put DHW as priority, so I unplugged the DHW electrical feed and sure enough, it fired and the zones all had heat. Later in the day I plugged the DHW in, and the supply temp dropped abruptly and no longer put out hot water to the three zones. (DHW is set to 130 degrees.)
I've turned the unit off, waited and then on again, even disconnecting power, but no luck. For tonight have unplugged the DHW so we'll have heat. Any one have a similar experience/suggestion? A call to Navien tech suggested it could be a three-way feeder valve, but would only talk with a licensed contractor. I would not do this myself but wanted to ask about it.
On a different note, after reading the threads here I'm wondering if our unit is correctly "tuned" as the return feeds are awfully hot, and I'm now doubting our unit is condensing appropriately to maximize its efficiency. From scanning the PCB readout, could this have a 170 set supply and return of 140 degrees?
Appreciate the help and all the amazing knowledge in this group.
We had no heat this morning as the Navien displayed a low water pressure code. I noticed a small drip in a copper pipe connected to an air vent which must have caused the low pressure, called in a plumber who fixed it and the unit subsequently fired up. Indeed, hot water went through the PEX pipe and we thought all was well, so he left. A few hours later, noticed house was not getting any warmer and it seems the Navien supply temp never went higher than 134 degrees. (It normally reads "P 26.8 and S 168" as the remote is set to 170 degrees.)
I've read that the Navien will always put DHW as priority, so I unplugged the DHW electrical feed and sure enough, it fired and the zones all had heat. Later in the day I plugged the DHW in, and the supply temp dropped abruptly and no longer put out hot water to the three zones. (DHW is set to 130 degrees.)
I've turned the unit off, waited and then on again, even disconnecting power, but no luck. For tonight have unplugged the DHW so we'll have heat. Any one have a similar experience/suggestion? A call to Navien tech suggested it could be a three-way feeder valve, but would only talk with a licensed contractor. I would not do this myself but wanted to ask about it.
On a different note, after reading the threads here I'm wondering if our unit is correctly "tuned" as the return feeds are awfully hot, and I'm now doubting our unit is condensing appropriately to maximize its efficiency. From scanning the PCB readout, could this have a 170 set supply and return of 140 degrees?
Appreciate the help and all the amazing knowledge in this group.
