Why does boiler kick on in summer heat?
My main question is why does the boiler run in the summer when all the thermostats are turned way down and so there should not be any “calls” for heat coming from the thermostats. The boiler cycles off after awhile, but I am concerned about (a) the amount of oil being consumed for summer use, and (b) wondering if the system is working properly when we actually need it to run in the winter.
Here is some background on us. We moved into our 1880 house this winter and are still getting to know the ins and outs of our new old house. We live in Massachusetts and heat with an oil fired Burnham (model 3W) forced hot water boiler. Our house has about 1800 square feet, but a whopping 4 zones due to incremental renovations over time.
Also, I think that Burnham has discontinued its 3W model so I am doubtful that I could obtain a user’s guide to this boiler. Thanks in advance for any guidance you can offer.
Replies
What is your source of hot water?
If it is either direct or indirect from the boiler then the boiler will run from time to time to generate the hot water.
The boiler is only used for heating our living space. We have a separate gas fired hot water heater for all of our hot water needs. Thanks for helping me to define the question.
heat exchanger to make hot water. Does it come on when you shower?
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As I said to Bill Hartmann, the first replier, this boiler should be heating water and continuously recirculating the same water, but not for any use other than heating our living space. Thank you.
Do you have a low limit on the boiler? Try disconnecting the thermostat wires and see if it still fires
I may have a "low limit", but I don't know. Would you please tell me what a low limit is? I am reluctant to disconnect anything because I may not be able to reconnect without paid assistance. Thanks.
A low limit sets a minimum water temperature for the system regardless of thermostat calls for heat.With the old gravity systems( even modified with a pump ) the large diameter pipes and cast iron rads add up to a huge volume of water if this is allowed to cool due to long off cycles the time lag between the themostat calling and feeling warm is huge.Also the expansion of the pipes is noisy and hard on the boiler sections.Some people feel that keeping the boiler warm helps to reduce condensation /corrosion of the sections.This I have some reservations about!!With the use of set back thermostats especially at the start and end of the heating season long off cycles are likely and may have been another reason for the low limit.IMHO I would turn off the power to the boiler and shut the oil tank valve for the summer
Good explanation of the low limit feature. I think that this must be what my boiler is doing. Thanks for your posting.
You are welcome.I have an old hydronic system (coal converted to oil) which I subsequently converted to a high efficiancy gas.I still use black iron pipes and often tinker with the control systems to try and squeak a bit more efficiency out of it.Used to be a licenced fitter in a past life!
Keeping the water in the system warmish might help prevent condensation on the outside of the boiler and excessive rusting if it's in a basement or other "high moisture" area.
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Others here would know better, but don't some boilers cycle as a self maintainence feature?
The former owner of our house did mention that he thought that having the boiler cycle on occasionally throughout the nonheating months would be good for the system. So, we may have a self maintenance feature on the boiler. If we do, then I would like to turn it down (if such a thing is possible) because the boiler seems to be overdoing the self maintenance. How likely is it that I have both a low limit issue and a self maintenance feature at work here? Thank you.
Hi - just a quick thing I thought of...
Isn't it the job of the boiler to make hot heating system water (and that's all it "knows")- and the job of the thermostats to kick on the booster (circulator)? I always though the boiler and circulators (zones) don't really "talk" to each other.
I'm thinking that the boiler has a reservoir and it'll keep that water in the reservoir hot - on the off chance that you'll ask for heat in the house. The thermostats won't be calling for circulation, but the boiler doesn't know that, it just does it's job of making 140 degree (or whatever) water.
So I can't speak in terms of what the 'Old Timers might recommend for the healthiest thing for your boiler, but I would think that the simplest solution, if it really bothers you in the summer, would be to flip the boiler switch to "Off" until it gets chilly in the Fall.
Edited 7/23/2005 10:12 am ET by JasonD
I think I agree with Jason. I have a gas boiler, and it keeps the water in the boiler at a certain temp, regardless of calls for heat from the thermostat (which kicks the circulator pump on.)
I just turn off the gas valve when summer comes. In fall, I clean out the boiler burners and give it all a general cleaning, then turn the gas back on and light the pilot.
It's an old boiler, and I would guess that newer ones are more efficient and have the boiler "talking" to the the circulator, and not heating water unnecessarily.
Pete Duffy, Handyman
Your theory makes a lot of sense to me and then I read the reply from PeteDuffy and he concurs. I did switch off the boiler this summer because I didn't want to see another oil bill until fall. Thanks to everybody for helping me to understand my heating system.