Adding insulation to oil-fired boiler?
I have a 12 year old oil-fired boiler in my basement. It is quite a large unit standing about 4 feet high and approximately 2 x 2 on plan. I think it has a small water tank inside that it is kept hot at all times as I have noticed that the burner comes on even when none of the controls are calling for heat.
My problem/question relates to the fact the boiler gets quite hot on the outside. It is hot enough that a rubber handled screwdriver will have the rubber deform if left on the top of the unit, and it makes the basement very warm. It is quite uncomfortable in all seasons except mid-winter here in New Hampshire.
I would like to add another skin of 2″ foil backed solid foam insulation directly to the surface of the existing “box” and I would not cover the zone relay box or any other controls and motors etc. I am sure that this would cut down on the heat being “wasted”, and should reduce the amount of time the flame has to come on just to keep the tank hot.
Do you have any thoughts about whether or not this is a good idea or will this negatively impact the boiler in some way?
Thanks
Peter
Replies
I would leave it alone. Also, I think that if rubber and plastic is deforming, the appropriate insulation wouls be higher temp, like Kaowool, or another refractory. But given the it is all OEM, I would leave it as is.
Make sure that the boiler is not set at a too high temperature. Did it always get this hot?
Does the boiler get yearly maintenance by a REAL heating pro?
We've been in the house for about 3 years and it has always been getting this hot in that time.
We get it professionally serviced every year, and their general comments are that it is in pretty good condition considering the age.
Peter
Regarding the temperature setting, I have a vague recollection that it is set to 180, but I will check tonight.
Is there a recommended temperature setting for this kind of boiler?
Peter
180 degrees is a typical setting for boilers. Some systems are designed for either lower or higher, but if that is what the tech has it set for then it should be correct.
Just curious, what makes your hotwater for the shower and sinks etc?
Regarding the domestic hot water supply, there is a separate hot water exchanger on its own zone, where the hot water from the boiler goes through a closed loop of coils in a tank surrounded by water that gets heated for domestic use.
Peter
It is *possible* then, that you may not need your boiler to maintain 180* water. There are a lot of "if's" and "it depends".
You should get a really good heating pro and discuss lowering the max temp some. It could save you some money on fuel. Also, the hotter the water the more noise the pipes make. But you should get that piping rearranged so it does not make so much noise from expansion.
Ask the heating pro about "Outdoor reset". Maybe it will work with your present system,, maybe not. Basically it adjusts the boiler temp depending on how cold it is outside. On a REALLY cold day you get max high temp. On days with say, 50 degree temps outside the boiler max temp is lowered some.
peterwn
OK accept the fact that you have an inefficent system.. Firing up a whole boiler just for a pot of hot water for tea is seriously wasteful..
If you don't want it hot year around try this,
Buy and have installed a electric hot water heater.. in the summer switch over to it, in the winter switch back.. heat lost inside the house isn't really lost! It warms the house.. remember warm air rises so whatever happens in your basement will eventually warm the upstairs..
The reason I suggest an electric unit is because they are cheap to begin with so we aren't speking about a great deal of cost here plus they don't need their own chimney which can be a major expense. Finally oil is a finite resource bound to get more expensive in the future. electricity is avialable and as oil gets more expensive solar wind and other power sourches will come on line holding down electrical costs relative to oil..
I agree with PachoqPhil and Frenchy: Running that puppy all year long is really wasteful. Install a separate water heater, and control the "boiler" (how could it be set to 180 degrees if its a boiler???) temp in spring and fall. Shut it down & have it serviced over the summer when the guys aren't busy.
If you have any air conditioning you're having to remove the furnace's heat, too...
Brooks
If your boiler is like mine, it must be maintained at around 125 degrees to avoid condensation. I added fiberglass insulation and the boiler was able to maintain this temperature with about 1 cycle every 6 hours. Fortunately, the hot water heater (like yours) needs boiler water at about the same rate. You probably need better controls like a tekmar 260, http://www.tekmarcontrols.com/prod/260.shtml
This control will run the boiler to 180 degrees for hot water than post purge the boiler.
For heat it will run the boiler to whatever is need depending on the outside temperature.
I put foam over ALL the pipes coming and
going out of the boiler. THe basement
was noticeable cooler and the boiler
cycled less. I run the boiler at
160 only on really cold days other wise
140 high limit seems ok. Maybe the
circulators run longer but they are only
.7 amp so no great loss.
You could also pipe the coil into
the hotwater (electric) heater
inflow using less electricity in
the winter. In summer, turn off
the boiler or set it back to the
lowest setting. See if you can
keep track of the fuel usage in
the warm months at idle compared
to turning it off. Maybe the amount
of $ savings will make it worthwhile to
withstand some condensation damage.
Boilers may, over the long haul, be
cheaper than keeping one alive longer
by running it all the time.
What kind of boiler do you have - steel, cast iron? 3-pass? Is it oil or gas fired?
Unless you have a boiler meant for such a low temp setting and a stainless steel liner, you might want to get a good CO detector for when that chimney starts crumbling within iteself. And pickup all the boxes off the floor near the boiler for when it rusts out and leaks water from condensing inside.
All kidding aside, unless your setup is meant for low temps, that 140* high limit can be dangerous. Proper boiler temps will keep YOU and your family alive longer in the long haul.
Edited 10/31/2006 8:15 pm ET by PatchogPhil
Thanks to you all for the input and ideas.First in response to PatchogPhil, it is an oil-fired unit and I'm not sure if it is steel, cast iron or anything else. The previous owners did not leave us any manuals or documentation, but I'm going to search the web to see if I can dig anything up.To others who have suggested replacing the boiler, I guess that will happen in time, but there are other demands on my cash flow right now. When I do look at replacing I will be investigating newer "on-demand" boilers/furnaces including outdoor temperature "feedback" and I'm also hoping to get rid of the domestic hot water exchanger as well. I'm not sure if you get these for use with oil but I'll investigate closer to the time. I'm sure these things are getting more efficient all the time anyway. I'm glad to hear someone has insulated their unit without the thing blowing up. From a thermodynamic perspective I can't imagine why adding insulation to a boiler would be bad (apart from accidentally covering up motors and controls and having them fail) but it's always good to get other perspectives. I like the idea of insulating the pipes as well - sounds like a good spring project.I'll see if I can find a good heating pro to give me some insight into all the options - insulating, new controls, new boiler. Who knows, depending on costs and savings it may be worth replacing the boiler sooner rather than later.
What does it mean to "post purge the boiler"?
Hi goldfreaz,When you say you used fiberglass insulation, is that the regular pink stuff you normally put in walls. If so, how did you hold it in place around the boiler?
Post purge means the circulator runs about four minutes longer than the burner, thus getting some of the heat out of boiler before it is lost up the stack.
I put the boiler on six inch legs and stuffed pink fiber glass between the cement floor and the boiler. Also, I stuff more white fiber glass from an old hot water heater between the boiler's sheet steel and its cast iron. I would like to fabricate a bigger shell and add more fiber glass, but I think most of the heat now is lost up the stack.