Old Bryant steam boiler, and duty cycle

ethicalpaul

My system is better now than back then and it runs with just 1 oz of pressure now during normal heat cycles.

Block your main vents before a heat cycle to see if it builds some.

The top of the pigtail stays cool pretty well, but after an unnaturally long call for heat I’ve seen mine get hot

Precaud

ethicalpaul said:

My system is better now than back then and it runs with just 1 oz of pressure now during normal heat cycles

Glad to hear it! What was the caause of your system's pressure buildup?

ethicalpaul

It was a lot of things. First it was no main vent, then there was bad near boiler piping, then there was bad water chemistry for awhile (too high a ph, my fault). I have lowered the manifold pressure a bit. I don't remember where in all my changes I made those videos so I'm not sure which of those made the big differences (but certainly the lack of main venting did!)

Kjmass1

> @PMJ said:
> (Quote)
> Right, the ratings are always for the total EDR(equivalent direct radiation) of the installed radiators not the house sqft to be heated. So I have 1000sqft(EDR) of installed radiation. The house itself is about 3500sqft.

Holy smokes! You have 240,000btu/hr of radiation. Your heat loss without even doing a Manual J is probably 70k/hr worst case for 3500sf. Under 50k if it’s only 2400sf heated.

Jamie Hall

The wonder is that @PMJ has made his situation work as well as it does -- which, from what I understand, is very well indeed. It has taken some ingenuity on his part. Go back and look at some of his previous posts and comments to see how he did it. A lot of good ideas there.

PMJ

Kjmass1 said:

> @PMJ said:

> (Quote)

> Right, the ratings are always for the total EDR(equivalent direct radiation) of the installed radiators not the house sqft to be heated. So I have 1000sqft(EDR) of installed radiation. The house itself is about 3500sqft.



Holy smokes! You have 240,000btu/hr of radiation. Your heat loss without even doing a Manual J is probably 70k/hr worst case for 3500sf. Under 50k if it’s only 2400sf heated.

It's all heated plus a 2-1/2 car garage.

It sounds like a lot until I thought about how the original coal fired must have run. I didn't see how the delicate pressure based damper adjustment could possible work with the installed radiation(whatever it was) anywhere close to full. When radiators hit full with a big boiler running the pressure builds quickly. It would be unworkable to control there. So I think they installed a lot of extra knowing filling would never be an issue. In my house having the radiation full continuously would roast everyone even at -20F. I am convinced that was never the plan. They installed a lot of extra and modulated on tiny amounts of pressure that would never change suddenly. This mild winter rads have warm feed pipes plus a few sections at the top - rarely more than that. But if you walk up to one it is sort of always that way. I like how even it is.

I quickly realized that I didn't need my radiation even 1/2 full on design day if I cycled the boiler to have them warm all the time, more like the continuous days. Heat was more even too. And it really didn't take that many more cycles.

I also think the coal fired boilers were "big" on a max capacity basis. But they really couldn't be run on "high" fire. I think they were big boilers modulated in the middle of their range. Big in relation to the actual demand, but big enough that a relatively small damper change in the middle of the range actually did something. I doubt those controls even have the capability to use a very high percentage of the total theoretical range from zero to "max", whatever that was. With our boilers we actually have max and zero as options, they didn't.

Jamie Hall

You really don't want to have a big coal boiler on max - unless you are right there to babysit it!

PMJ

Jamie Hall said:

You really don't want to have a big coal boiler on max - unless you are right there to babysit it!

Agreed. Maybe why those things were such monsters.... with a relatively small fire inside that was more easily managed even in the bitter cold.

Precaud

The original boiler in this house was wood-fired. The owners were loggers, they owned the town's lumber yard, and the house was located at the entrance to the property. Burning the softwoods common to this area (pine, pinon, cedar, juniper, etc), firing rate would be hard to control... it would have always been burning at or near max and require constant feeding and attention. Mabe that's why they had six boys

The things we did for love heat!

Precaud

I just got my first full-month nat gas bill (January) since putting the Bryant back in service. I have data from 2003 to 2005 to compare it to. Therms used in January in those three years averaged 190 (hi=210, low-170). In the mid-90's, I remember there were a couple years where it was 250-275.

This year it was 100. Quite a drop.

Precaud

In another thread, I asked about boiler anatomy, and decided to remove the side cover from the Bryant and see what it looks like. The "7S" model number prefix obviously refers to seven sections.

Looks pretty darn clean inside for such an old beast!

mattmia2

is that thermostat wire asbestos or is it just some natural or synthetic cloth?

Precaud

Looks like a cloth/fabric jacket, which was common back then. Part of the house wiring has it too.