Coalpail.com Forum

Pacowy wrote:The system will slide backwards if it can't put BTU's into the radiation as fast as the radiation puts them into the living space.
Mike

Pacowy wrote:I have a couple of concerns with this whole discussion, and the ways it seems to try to put a happy face on the problems associated with undersized boilers. First, the heat going out from the boiler needs to at least match the heat transfer that is performed by the installed radiation (i.e., the heating load), not any "heat loss" estimated through other means. The radiators don't care what a computer program computes as a heat loss; they will transfer BTU's at well-defined rates until the controls tell them they can stop. If there has been a setback, an open window or door, a boo-boo in the heat loss program, a spouse pushing up the thermostat because they feel cold, etc., installed radiation will transfer BTU's up to its own capacity without regard to any heat loss computation. The system will slide backwards if it can't put BTU's into the radiation as fast as the radiation puts them into the living space.

On a related note, I think all of the people proposing to address the low output problem by changing the controls so the circulator is not interrupted by the low limit should relax. I'm not a hydronics guy, but I'm pretty sure that any system in which playing with the circulator at the low limit would make a measurable difference in the ability of the boiler to carry the load has already been confiscated by the Conservation of Energy Police, because AFAIK it would violate the first law of thermodynamics. As long as the stoker is running (and I can't imagine why it wouldn't be when the system goes under the low limit) the BTU's are going into the boiler water; if the system won't get off the low limit, the problem is that the radiators are giving up the BTU's faster than the boiler can make them. To be clear, I'm not saying it would be a bad idea to have the circulator run independent of the low limit (e.g., for the reason whistlenut has raised). I'm only saying that it appears to be impossible for that to form any meaningful part of a solution to the underlying problem of the boiler being too small.

Mike

Pacowy wrote:I have a couple of concerns with this whole discussion, and the ways it seems to try to put a happy face on the problems associated with undersized boilers. First, the heat going out from the boiler needs to at least match the heat transfer that is performed by the installed radiation (i.e., the heating load), not any "heat loss" estimated through other means. The radiators don't care what a computer program computes as a heat loss; they will transfer BTU's at well-defined rates until the controls tell them they can stop. If there has been a setback, an open window or door, a boo-boo in the heat loss program, a spouse pushing up the thermostat because they feel cold, etc., installed radiation will transfer BTU's up to its own capacity without regard to any heat loss computation. The system will slide backwards if it can't put BTU's into the radiation as fast as the radiation puts them into the living space.

On a related note, I think all of the people proposing to address the low output problem by changing the controls so the circulator is not interrupted by the low limit should relax. I'm not a hydronics guy, but I'm pretty sure that any system in which playing with the circulator at the low limit would make a measurable difference in the ability of the boiler to carry the load has already been confiscated by the Conservation of Energy Police, because AFAIK it would violate the first law of thermodynamics. As long as the stoker is running (and I can't imagine why it wouldn't be when the system goes under the low limit) the BTU's are going into the boiler water; if the system won't get off the low limit, the problem is that the radiators are giving up the BTU's faster than the boiler can make them. To be clear, I'm not saying it would be a bad idea to have the circulator run independent of the low limit (e.g., for the reason whistlenut has raised). I'm only saying that it appears to be impossible for that to form any meaningful part of a solution to the underlying problem of the boiler being too small.

Mike

I'm in agreement with this.

At some point, there won't be any 'idle time' involved. You'll be making heat as fast as you can make it, and the system is going to equilibrate to the setting on the boiler, either LL orHL.

Whether or not that raises, lowers or holds the temperature steady in the dwelling becomes a matter of what the heat loss is, vs the output of the radiation

windyhill4.2 wrote:Years ago I heated a totally uninsulated block wall garage with no ceiling insulation, 1200 sq. ft.,with an old hot air mobile home unit 80k -- hot air ! he has hot water & should be able to easily heat 900 sq.ft. with that unit ! Set the water temp up,set controls to run unit more consistently,stop the yo-yo effect that is not allowing system to make heat.Install those pins as oliver power said,get the circulator running & start heating that little house up !! Some of you guys need to step outside & clear the fog from your brain,if his boiler is under sized it would be firing 25 hrs/day -nonstop,he says boiler gets water temp up & cycles off,get the whole system working together & problem will be solved, KEEP IT SENSIBLE SIMPLE,good grief !!!

If you want to keep it sensible and simple, remember that the boiler is storing any BTU's imparted to the water when it is running below the low limit. Whether they are released continuously or in batches, the overall boiler output and its relation to the radiation to which it is connected are unchanged.

KLook wrote:
And I am in disagreement. For many reasons but I will be short. Oliver and I are the only 2 that have the same situation as this gentleman. We have made our little boilers that could work. As Oliver said, I would think he would try what those with the same experience have found to work FIRST.
If it doesn't work then all you experts can chime in and save the day. I am amazed at the sniping by people when the guy needs some help. It adds to his confusion.
Kstills, your premise that the system will catch up is just wrong. I said it way back but you ignored it. My boiler would drop to 140 or less and then it would just churn for days until the load was decreased. You are not thinking about this because you said you could run 160 water, and 160 will not work for an undersized boiler. It needs to start out at about 200, or better and drop to 160 maybe. It needs to have a head start, put out all the heat it can store, and get fired up just as soon as a zone calls. Even better with Olivers increased pins so long as it doesnt go over the high limit and dump.

Kevin

Sting wrote:

Pacowy wrote:The system will slide backwards if it can't put BTU's into the radiation as fast as the radiation puts them into the living space.
Mike

and if the circulator is not running due to the diafunctional Triple Aquastat in control -- the above has EVERYTHING to due with boiler size -- or as you cannot get off your soap box enough -- boiler undersize

KLook wrote:

If you want to keep it sensible and simple, remember that the boiler is storing any BTU's imparted to the water when it is running below the low limit. Whether they are released continuously or in batches, the overall boiler output and its relation to the radiation to which it is connected are unchanged.

Wrong, the radiation will not put out heat with low water temps. Just the way it works. It is designed for 180 water and that is what is required to get the rated Btu's/ft. CIrculating warm water will keep the pipes from freezing and the house, but he will be cold.

Kevin