Aquastat settings It's that time of year
My boiler used to produce domestic hot water, but now it does not (electric water heater).
I have my HI set to 190*F. LO is set to 120*F. DIFF is set to 10*F (lowest I can set).
I'm only home and running the heating system for short blocks of time (i.e. 6AM to 8AM, and 6PM to 10PM)--the rest of the time I keep the house at an "away" temp of about 60*F.
So I'm looking to be able to get the house up to temp (68*) from my "away" temp (60*) relatively fast.
Do these settings I have make sense for that? Previously I had lowered my HI to about 160* thinking it would cut my standby losses, but now I realize that the HI only comes into play when the boiler is running due to heat being called for--is that right?
On a related topic... I keep the second floor of my house (unoccupied) set at 50*F all the time, but there are some heating pipes that run through a knee-wall attic space which could be susceptible to freeze up. It has a separate thermostat and circulator pump.
I'm considering a couple of options to combat this...
One option is electrically heated tape (I'm hesitant to try this because it will mean installing an electrical outlet in the attic and it also is about 40-50 linear feet of pipe to protect (supplies and returns for the heating system up there).
Another option I was thinking about was installing some sort of a timer/relay on the circulator such that it would run for say 1 minute out of every 20 minutes. That would hopefully ensure that the pipes always stay above freezing. This wouldn't be calling for heat during the minute, just running the pumps... if the system did call for heat (because it dropped below 50 up there, or because I turned the thermostat up) the system would just operate normally.
jack bGone FishingPremium,MVM
reply to bemis
The HI is the upper limit, that shuts the burner when it reaches the setpoint during a call for heat.
LO minus the differential is the point where the burner fires for domestic hot water and will raise the temperature to the LO limit setpoint. It is also where the circulator will stop if it's running, in order to keep the boiler temperature hot enough for domestic use.
If you no longer use the domestic HW, set the low limit as low as it will go and the set the differential at the highest number.
As far as the pipes in the attic space, just insulate them and you should be fine. 45 feet of heat tape will use roughly around 200 watts.
190 might be higher than you need for the high limit setting, I would try lowering it, it might help cut fuel consumption as long as the space heats up the way you want it to, while set lower.
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