1905 one pipe in 2014

icecube

Good day to all. I seek advice for my one pipe 87 rad system with a WeilMclain LGB steam boiler, Honeywell communicating thermostat with equipment interface module. Problem 1; thermostat calls for heat even when it is apparently satisfied (setting matches reading) . I know these thermostats are programmed from the factory to supposedly give even gradual heat but when I override and hold setting the problem still persists. So then the pressure starts to build up (2psi). Problem 2; pressurtrol can not be set low enough to stop this excess. I have ordered a vaporstat and will install that when it arrives. THE QUESTION IS : is a thermostat still the best way to control this steam boiler or is there a better way? To have the burner fire up and heat the water to steam ,then shut off and let it cool to whatever degree and then start up again seems somewhat inefficient yet running all the time seems inefficient as well.
NOTE* This boiler is in Canada ; winter temperatures are very often lower than -20 and consistently drop to -40.
All responses are appreciated

nicholas bonham-carter

I have 55 rads on a 1,050,000 BTU one-pipe system, controlled by a honeywell Visionpro thermostat, with a remote indoor sensor (mounted in the coldest apartment). The control unit of course is away from prying fingers! I am not using any night time setbacks, due to the extra fuel they burn to regain the higher temperature.
I have worked on my main venting, to the point that the air escapes from the main vents at one or two ounces, verified by a 0-3 psi gauge. Massive main venting is the key to efficiency and comfort, and lack of it may cause short-cycling as you set your new vaporstat to ounces of pressure.
Steam can rise up into the radiators very quickly, shortening the burn time of each call for heat.
Some people have used the Tekmar 279 steam control with success, but it is expensive to buy, and could be difficult for the average maintenance person to program, so for the moment, the thermostat is satisfactory.
Post some pictures of your boiler supply piping, and maybe we can advise on any system tweaking.--NBC

icecube

Hello Nicholas. Thanks for the response. The near boiler piping is a duplicate of the WeilMclain illustration for one pipe systems, I have 5 of the big Gorton vents on the main , heat does come pretty fast and I do have the thermostat not at the end but further out than the median. Correct me if you feel I am wrong in the following logic: I am thinking the vaporstat will likely cut out the burner before the thermostat is satisfied but from experience I know the radiator will be hot at this point. So then when the pressure drops back down and the burner is reignited it will follow that pattern until the thermostat is satisfied. So the end result should be more even heating and a boiler that does not cool down as much between burns. Maybe? Reality always seems to want to mess with theory

nicholas bonham-carter

If the short cycling takes place before the radiators are full of steam, then it is a sign that the venting could still use improvement.
If it still cycles when steam is in the radiators, then a 2-stage valve might save money. A big boiler may be already so equipped, and just not have that feature engaged.--NBC

Jamie Hall

On the cycling on pressure. Assuming that this is happening when all the radiators are full, it simply indicates that the boiler is somewhat larger than it needs to be. Two stage firing (controlled by vapoustats) would help, if that's available. As to the loss in efficiency, typical cycling on pressure does not involve the kettle coming very far off the boil and the resulting loss in reheating the water is minimal. And it is not enough to justify the expense of a fancier control than a decent thermostat.

vaporvac

icecube said:

Problem 1; thermostat calls for heat even when it is apparently satisfied (setting matches reading) . I know these thermostats are programmed from the factory to supposedly give even gradual heat but when I override and hold setting the problem still persists.

Apparently this is the nature of the beast. They don't read as fractions, although the are registering that way. So the swing could be just less than 1 degree. I recently asked the same question and the consensus was that my system must be matched to the edr. Mine will come on for a minute before going off. However, this if often at negative pressure, so I assume it's pushing steam around to some extent. It is annoying if I see it during positive pressure as there's no way it's on long enough for steam to reach the rads.

I think your situation is different because it's able to build pressure. That would mean your venting isn't adequate or it's just really cold on start-up. Once temp is reached you shouldn't be building anymore pressure. I have twinned boilers and I can shut one off and continue to heat my house. Definitely do as suggested Jamie and NBC suggest and see if your valve is two-stage. P.S. Where are you in Canada? I'm a former Montrealer.

icecube

Wow . Great insight from everyone . Thank you . I looked into the valve and I believe it is 2 stage , I'm sure the supplier and installer were unaware of this . Also , the tekmar 279's cycle time feature sounds like a potentially good advantage as well . I did not see that feature when I looked it up . NEXT QUESTION : does the cycle feature of the 279 work in conjunction with other settings or would the cycle setting basically override everything ?
As far as how it operates now ; the thermostat is , in my opinion the problem as it seems way to slow or has too much leeway as it doesn't turn off until it's basically above the setting and doesn't turn on until it's well below the setting . So like I said it's still calling for heat when it's reached its set point ( room get too hot , room get too cold ) . What is the consensus about these " smart" thermostats being used on steam systems ?
Sask btw

nicholas bonham-carter

The only "smarts" those thermostats have is the ability to calculate an on time for temperature recovery, which is not much use if you are keeping the temperature constant, as we think is more efficient.
Hook up that second stage of the gas valve, with a pressurestat, and the system will be better off, with longer cycles, consuming less gas.--NBC