Aquastat issue with my oil boiler outdoor wood boiler set up?
#1
11-14-08, 04:45 PM
Aquastat issue with my oil boiler outdoor wood boiler set up?
I have directly plumbed my outdoor wood boiler into my oil boiler. The outdoor wood boiler is set at 190 degrees, meaning it begins calling for heat at 185 degrees and stops when it reaches 190 degrees, the secondary comes in at 180 degrees because we have not had any cold (It has not gotten below 20 yet) I have not seen water temps near that level. The outdoor boiler is connected to the indoor oil boiler with well insulated 1 inch pex piping.
The cold start oil boiler has a Honeywell aquastat (Type L8148A) that is set at 160
Most of the time every thing works great, and the oil burner does not kick on. However, when several zone of the house call for heat at the same time cool water gets comes into the boiler at at a rate fast enough to trigger the aquastat and have the oild burner kick on. The temp guage at the front of the boiler remains up between 185 and 190 degrees, but I have a 2 inch line dumping in cool water and that seem to trigger the aquastat. The oil boiler only runs for a minute or two. Just long enough for the cool pipe water to circulate out of the pipes.
I am at a loss as to what to do. I tried setting the aquastat to a lower setting but it did not help and I could not leave it that low as it means I would need to lower the temperature of my domestic hot water, as it is set at 160 (there is a tempering valve so actual tap water temp is lower)
Is there a way to install an aquastat at the wood boiler so that as long as that water is above 175 the oil boiler will not come on? Is there another solution I am missing?
Thanks, any help would be greatly appreciated.
The cold start oil boiler has a Honeywell aquastat (Type L8148A) that is set at 160
Most of the time every thing works great, and the oil burner does not kick on. However, when several zone of the house call for heat at the same time cool water gets comes into the boiler at at a rate fast enough to trigger the aquastat and have the oild burner kick on. The temp guage at the front of the boiler remains up between 185 and 190 degrees, but I have a 2 inch line dumping in cool water and that seem to trigger the aquastat. The oil boiler only runs for a minute or two. Just long enough for the cool pipe water to circulate out of the pipes.
I am at a loss as to what to do. I tried setting the aquastat to a lower setting but it did not help and I could not leave it that low as it means I would need to lower the temperature of my domestic hot water, as it is set at 160 (there is a tempering valve so actual tap water temp is lower)
Is there a way to install an aquastat at the wood boiler so that as long as that water is above 175 the oil boiler will not come on? Is there another solution I am missing?
Thanks, any help would be greatly appreciated.
#2
11-14-08, 05:20 PM
A couple of recent threads have adressed this situation pretty well I think ...
What you want to do is disable the oil burner from firing when you have a wood fire going.
Let me see if I can get links to those threads... standby ...
What you want to do is disable the oil burner from firing when you have a wood fire going.
Let me see if I can get links to those threads... standby ...
#3
11-14-08, 05:46 PM
OK, here's the thread :
http://forum.doityourself.com/boiler...-aquastat.html
It's long, but there's lots of info in there ...
Perhaps the easiest thing to do is if you have a Beckett burner or any burner with a primary control that has T T terminals on it. There will be a jumper on these terminals. Get a cheapie non-programmable thermostat, and some wire, run a thermostat in the home and connect to the T T terminals.
Push that t'stat DOWN when burning wood, and UP when burning oil ... putting it below the temp of the room thermostats will prevent the burner from firing whenever the room temp is being maintained by a wood fire, and vice versa when you push it above.
http://forum.doityourself.com/boiler...-aquastat.html
It's long, but there's lots of info in there ...
Perhaps the easiest thing to do is if you have a Beckett burner or any burner with a primary control that has T T terminals on it. There will be a jumper on these terminals. Get a cheapie non-programmable thermostat, and some wire, run a thermostat in the home and connect to the T T terminals.
Push that t'stat DOWN when burning wood, and UP when burning oil ... putting it below the temp of the room thermostats will prevent the burner from firing whenever the room temp is being maintained by a wood fire, and vice versa when you push it above.
#4
11-15-08, 05:43 AM
Wow, lots of information
It was a lot of information to digest but in short I think it says to install a second set of thermostats in the house. That should not be a problem for 2 of the four zones but will be a challenge for the other 2. How do I manage a second aquastat for the domestic hot water?
#5
11-15-08, 08:13 AM
No, not a whole 'nuther 'set' ...
just ONE ... a cheapo non-programmable one.
Two wires going to the TT terminals on your primary control. (NOT the aquastat, make sure you understand the difference between the PRIMARY CONTROL and the AQUASTAT)
This thermostat will enable or disable the BURNER ONLY, leaving all other control functions intact.
Remember, you can only use this extra thermostat idea if your oil burner has a primary control with a jumpered set of T T terminals.
If you set the thermostats in the home to say 70°, then when you are burning wood, you would set this additional thermostat to say 65°. As long as the wood boiler is able to maintain the set room temperature of 70, the EXTRA thermostat would always be satisfied, and the burner would never fire.
If the wood boiler is unable to maintain the 70 setpoint, and the temperature in the room dropped below 65, the burner would be automatically re-enabled, and maintain the room temperature at 65° ...
When you are NOT burning wood, and want to burn oil, you would set the EXTRA thermostat up at say 75°. With the room thermostats set at 70, the extra thermostat would never satisfy, and would keep the oil burner enabled... NOT running, but enabled ... the regular room thermostats will still be supplying the heat calls to the controls.
Was your wood boiler installed according to manufacturers specifications ? Were all the safety controls installed and functioning correctly ?
just ONE ... a cheapo non-programmable one.
Two wires going to the TT terminals on your primary control. (NOT the aquastat, make sure you understand the difference between the PRIMARY CONTROL and the AQUASTAT)
This thermostat will enable or disable the BURNER ONLY, leaving all other control functions intact.
Remember, you can only use this extra thermostat idea if your oil burner has a primary control with a jumpered set of T T terminals.
If you set the thermostats in the home to say 70°, then when you are burning wood, you would set this additional thermostat to say 65°. As long as the wood boiler is able to maintain the set room temperature of 70, the EXTRA thermostat would always be satisfied, and the burner would never fire.
If the wood boiler is unable to maintain the 70 setpoint, and the temperature in the room dropped below 65, the burner would be automatically re-enabled, and maintain the room temperature at 65° ...
When you are NOT burning wood, and want to burn oil, you would set the EXTRA thermostat up at say 75°. With the room thermostats set at 70, the extra thermostat would never satisfy, and would keep the oil burner enabled... NOT running, but enabled ... the regular room thermostats will still be supplying the heat calls to the controls.
Was your wood boiler installed according to manufacturers specifications ? Were all the safety controls installed and functioning correctly ?
