Btu requirements of American Radiator / Ideal boiler

SethYank

My customer has an old coal to gas conversion Ideal boiler. It has a gas valve capable of feeding 2100 CFH. I am thinking this is too big, her gas bills last year were @ 700 to 800 a month. Now granted the gas orifice is around 1/2" on a Gordon burner. I am tring to find out what this boiler was supposed to be rated at. The ID plate lists it as Size = G-29-T-8, and series = 29WT2B. What got me started down this path was the flame rollout on start up. I found out the honeywell diaphragm gas valve can be timed to open slowly and am getting the orifice to do so.

Steamhead

Wow, looks like an old Ideal Water Tube boiler. That was one of the better boilers of its day.

The Beacon book, here:

https://www.heatinghelp.com/systems-help-center/beacon-boiler-reference-book-boilers-made-prior-to-1959-part-1/

shows this boiler is rated 1540 square feet of steam radiation on coal when hand-fired, and 1680 with a stoker. Based on this my educated guess would be something like 700,000 BTU per hour input.

Have you done a combustion test?

bburd

Keep in mind that the gas valve capacity is only a maximum rating. It's the orifice that controls how much fuel is burned.

Have you measured the radiation, and clocked the gas meter to see how much fuel it's burning?

You don't indicate your location or the gas rates, but for a boiler that size in a large old house the monthly bills don't seem out of line.

SethYank

I understand the gas valve is a max flow rate, The current valve is 1 1/4 inch inlet / outlet capable of flowing 2100 cfh. Knowing the boiler is rated for 700,000 btu input I can down size the valve to a 1" which will only flow 1000 cfh, this should reduce her gas consumption. The customer is not in a financial position to replace the boiler, I am just trying to help her get by. I am not charging her for all of my time just trying to keep this boiler safe and functional, she is 88 and the proverbial cat lady. I am located in south central Pa. The upper passages have a light coating of carbon, but not bad. No I didn't do a combustion analysis or clock the meter can try that when I can spare a little more time. The orifice in the burner is huge about 1/2". The burner is just a straight horn with a pilot at the end with a Baso safety.

bburd

I greatly admire you for helping out your neighbor, but changing that gas valve will not reduce her heating bill.

The firing rate is set by the orifice (and the gas pressure regulator), but the thermostat is in charge and responds to the heating load in the house. if you reduce the firing rate, the burner will just run longer to satisfy the thermostat. The same amount of gas will be used. As @Jamie Hall says, sometimes basic physics is a ****.

Can anything be done to reduce the heat in parts of the home that are not used very much? That will certainly save fuel. I have even resorted to wrapping radiators in blankets in closed rooms, which works surprisingly well.

SethYank

In this instance I am thinking a longer run time would be good. this was originally a coal fired vapor system. A longer slower fire would get heat to more of the house. The current manifold pressure is 2.5 " wc. If I can figure a way to reduce the orifice I wont be dumping 2,000,000 btu in an hour. I was thinking the smaller valve would act as a restriction to flow for the gas lowering the instant dump into the chamber causing rollout. She typically lets the house get down in the low 50's before she turns the tstat up and then turns it down again so the boiler wont come on. The house also has steam traps that need rebuilt but again the cost stops her.

bburd

You are not dumping in 2 million BTU per hour. The orifice won't allow it. But certainly the flame rollout is a serious concern.

SethYank

I will clock the gas next time I'm there

mattmia2

if it is a vapor system and you are controlling the pressure from the boiler properly and the vapor valves are set properly it doesn't need the steam traps. Fix the pressure and the venting to get the whole system to heat.

Someone that knows what they are doing with combustion and draft needs to get the burner burnign correctly. If it is downfired too much it won't boil the water vigorously and more heat will go up the chimney than out in to the system.

bburd

@mattmia2 has a good point. What steam pressure is she running? Is it controlled by pressuretrol or vaporstat?

Steamhead

@SethYank , where in S. C. PA? I'm in Baltimore...........

SethYank

York, Pa

Steamhead

Right up the road!

EdTheHeaterMan

Reducing the gas pipe size, or the gas valve size, or even putting a smaller gas meter on your building will not lower your gas bill.

The fact that a gas valve has a capacity of 2100 CFH means that you can not use it on a boiler that requires 2150 CFH or larger. It will work on a boiler that requires 700 CFH just fine. If you use a valve with a capacity of 1500 CFH, the boiler will burn 700 CFH the same way that a 2100 CFH valve will work.

Youy can spend the time and money to pot a smaller diameter pipe and a lower rated valve and even get a smaller gas meter, as long as there is an orifices that will allow 700 CFH to pass thru it, then you will get 700 CFH to pass thru it.

If you purchase a valve that can only handle 300 CFH, then you will get a poorly burning flame and poor efficiency because the burner has combustion air capacity for 700 CFH but the gas train (the parts that control the gas flow like the valve, pressure regulator, secondary valve if equipped and connecting pipe diameters) are chocking off the gas flow.

I can guarantee that if you turn off the manual gas valve, there will be a very large savings because no gas can get thru a closed valve. However if you want to heat the building, that procedure will not work for you. If you cant afford the cost of the utility bills for the home, perhaps they should sell the home to someone that can afford to heat it and then purchase a smaller building with lower operating cost.

But don't waste your time fixing what isn't broke. Your logic is flawed.

mattmia2

If the distribution system needs maintenance or has been knuckleheaded that can use significantly more fuel.