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Posted by Pat S on January 25, 2005 at 12:20:39:
In Reply to: Re: Replacing boiler posted by HeatPro on January 25, 2005 at 11:10:47:
: As you have R-30 ceiling and R-5 walls, that does explain why your losses would be about 29 btuh per sq ft. The design at 70F DTD also explains why you don't maintain below 0F outside.
Good - I'm more at ease w/ my numbers, now.
: There are probably some things you could do at no cost, like set your temperature control on your boiler to the settings they were designed for when the house was built: 220F high limit, 200F low limit and 20F differential. The cast radiators were originally for steam which operates at 215F, so they can't be harmed by water warm enough to do the job. You probably have the settings lower than that in the interest of saving fuel.
Exactly - I run it at about 160F (180F H.L.)to save $, and now boost to 180+F for cold spells.I guess it does maintain, just at a prohibitively expensive cost on fuel. I am averaging $224/mo gas bills(annually) w/ Jan/Feb bills averaging $300+. I am sure I can lower these w/ more wall insulation and better windows, but for my situation it seems like the right time to upgrade my plant (it is 65 yrs old)as the wall insulation issue will probably never be > R-11 and that will only come at considerable expense and inconvenience.
: There is a bit of confusion yet, as you state you have an external coil and a domestic hot water coil, so they are conflicting information.
Sorry - I have an external DHW coil supplied by boiler HW. The water is very hard and I am sure it is limed up - but the DHW is sufficiently hot (no controls - only aquastat shut off/priority of HHW circulator. Basically, the boiler has temperature control and heats DHW only when boiler calls itself on. Circulator for HHW controlled by T-stat) but runs out during showers. I am sure the mixing valve should be replaced - but I think ultimately it is a problem with capacity. Probably could be fixed with a cleaning and correct control config on entire plant, right?