over heating

[jjz]

hi
i just installed a p&m bl 2840 and fired up yesterday. the thermostat is not connected although the fan is pushing through the coil on the furnace. the system also has a sidearm for the domestic. the aquastat for boiler fan is set @ 180 as recommended. yesterday with fan on low speed, the house got to 75. I shut the fan off and within the hour the supply temp was @ 210. (return @ 200) with little demand on the system what will prevent the boiler from boiling over.
thanks,
joe

 

[GENECOP]

Not enough demand, this time of the year is tricky if you are not setup just right...some of the more knowledgable guys might chime in....Heat Dump....you need one of those probably...be careful. There is a lot to designing these systems and having them work correctly, I have been at it for a couple of years and am still struggling and learning...

 

[maple1]

Smaller fires this time of year.

 

[brant2000]

Although it would be nice to have a fail safe heat dump, that will operate even in a power outage, I use a temperature controller to engage my furnace (heat pump) blower when the water gets to 200 F. This will then run until the water has dropped back down to about 185 F. These are really very cheap and simple to operate. Here is a no frills version you can get for about $10 ((broken link removed to http://www.ebay.com/itm/12V-Digital-LED-Temperature-Controller-Temp-w-Sensor-Thermostat-Control-Relay-/121438977331?pt=LH_DefaultDomain_0&hash=item1c4653bd33)). Just use the relay contacts in parallel with your furnace blower relay.

 

[Bob Rohr]

There will be a bit of a learning curve. I keep an eye on the imcoming weather to know how hard to stoke the fire.

Once the load goes away you either need a dump zone, or a buffer tank that can absorb some output until the fire settles down.

The shoulder seasons are a bit of a challenge to get all the fire and loads to match up.

Even if the stove could ramp down quickly, you don't want a smoldering low O2 fire that can cause creosote and high emissions. A small hot fire is a better burn for the small loadrabIf

 

[atvalaska]

i'm in the same boat ....the fire goes out/low and the heat climbs ...I have a lite load btus needed and it sits at idle then boom ... 1'm going to lower my water temp to 170/10.......

 

[jjz]

Thanks guys,
I also lowered the set point to 170 seems to be helping. Maybe a heat actuated three way valve with a unit heater in the garage as a heat dump?!?!
first year with a owb. hopefully works out ok, but then again can't be worse than last years bill for the old electric furnace lol.