Turbo for your oil/ hot water heating

[sodderboy]

My heating tech recommended an "outdoor reset" module for my oil burner.  I finally installed one myself, a Tekmar 256, and it really rocks.  The idea is to have an intelligent monitor decide when the boiler should fire rather than a simple "call for heat" switch closure.  The outcome is more even temperature control and less fuel usage.  A programmable thermostat can not do all that.
The reset monitors outdoor and boiler send temps and makes the burner fire decisions.  What changed is that for me, with a three zone system mixture of radiators and baseboards, the circulation pumps work more often and the burner less often.  Much less.
Our first perception was that it was consistently too warm, with no changes to the thermostats.  I reduced the them to 67 from 69.  Overnight is now only 62 down from 64 and it still feels warm.  I will be tweaking the controls into the cold season but I am already impressed with the operation.  It made a huge change in the home environment.
The hookup was quite simple with the two LV sensors and the HV boiler wiring and I saved $1100 doing it myself.  There is even an "AWAY" switch function that lowers the system to a set temp if you go away for a few days.  I used to have to do that on three stats manually.
I totally recommend the addition for comfort and energy conservation.  Even if you pay for installation it will be worth it.
Mike

 

[JohnRoberts]

It helps when analyzing this stuff to think of the heat flow as current, temperature is voltage, and house insulation or heat leaking from the house to the outdoors is like resistance between the inside voltage and the outdoor voltage (not unlike heatsink design and thermal analysis). You can think of the interior as a charged capacitor, and the outdoors as a much larger current sink.

Factoring in for the indoor/outdoor temperature differential can allow you to calculate or impute the rate of heat loss from inside to outdoors.

Adding hysteresis  can improve efficiency if burner runs longer, less times, but I don't know how much. With the thermostat setting it depends on the average indoor temperature, and there will be a small cost for running pump longer.

Comfort is good..  The most obvious thing from simple inspection is increasing resistance (insulation) can be a huge win-win. Reducing the indoor temp at night, can also be a winner, since A) you generally don't use most rooms at night, and B) it is colder outside at night so more heat is lost. Temporarily dropping indoor temps really saves energy, since heat flow is linear with temp difference. Dropping indoor temp 10" could make huge difference when not very cold outdoors, while less of a benefit when very cold.

[edit- my after-the-fact checkers were bugged by my "less of a benefit" comment when very cold. The benefit is the same no matter how cold it is outside as long as colder than inside. it is just a constant savings not a fraction of total, so it may seem less proportionately.

Being able to program temp vs time of day seems like a large potential saver. (tekmar makes a set back timer).

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OTOH we have my redneck heating system..

I am looking forward to see how this winter plays out. I have in-wall resistance heat, so my electricity bill can be significant. My large in-wall air conditioner decided to crap out about a month ago. so I replaced it with a combination air conditioner/heat pump. From the spec sheet the heat pump uses roughly 1/3 the current as resistance heating for making the same BTUs of heat, so I am optimistic that I can take a bite out of this winter's electricity bill.

I've only used it a couple times so far on very cold mornings, and it heats up the main room pretty quickly. Forced hot air heat is not as comfortable as baseboard hot water, but I am too cheap to throw a lot of money at this house.

My (cheap) in-wall heat pump, does not have time of day programming, but does have a remote control, so I could probably connect a IR led source to a cheap micro to mimic my remote control (looks like another DIY project), and manage my heat for day vs. night, maybe even tweak temps, but I'd be OK with turning it off at night for several hours.

In the past I connected a fan to a outlet timer to increase my resistance heat output during daytime. When fan is off, the in wall heater heats up just the static air right by it, but with fan blowing cold air on the heater, more heat is blown into the room. I set the time so the fan comes on an hour or so before I get up. It turns off before I go to sleep at night. 

If i do a DIY controller, I might sense outside temp too. I think the in-wall heat pump may do some of that already since it seems to cycle differently when it warms up outside.  There is lots of lag between indoors and outside temps (thermal mass).

JR