please help with boiler selection!

Brad White_164

First of all, do you know the connected EDR (radiator surface) that will be served by the boiler? Is the 750 SF you cite that number?

If 750 EDR is your goal, a net I=B=R output of about 180,000 BTUH would serve nicely. The gross output for piping and pickup would take this to 239,400 and at 80% efficiency gets you to the 300,000 neighborhood. I would do a double-survey of the EDR and insulate the piping to narrow down the margin a bit. To get 180 MBH net from 300 MBH gross seems somehow a hill to climb, even though we know the 1.33 I=B=R factor and all.

Secondly, the vent damper- there was talk here a couple of weeks ago advising against using electronic ignition and a vent damper versus a standing pilot particularly in humid environments. Personally, I have had EI and Vent Damper here in Boston for years with no problems FWIW. But there was a discussion.

As for purchasing a HW boiler and converting it to handle steam? Some boilers are hermaphrodites from the factory :) and you can select either steam or HW trim. I suppose if the boiler is one of those already, you have a shot. But I have to ask, if the boiler is now HW is it used? Can you even install it by code if not in place already?

In my experience, most steam boilers that are given a "gender change" are steam going to HW not the other way around, FWIW. I see no technical reason why it cannot be done if the core design supports both steam and hot water and the condition warrants it.

Jeff_66

Please help with boiler selection!

We need to replace our boiler for a one-pipe steam system. We have 2 quotes for a 300,000 BTU (approximately 750 square feet of radiation) boiler but only one of the models has a vent damper.

1. Can you recommend a good 300,000 BTU model that does come with a vent damper (or that can be retrofitted with one)?

2. Are there disadvantages to purchasing a hot water boiler and converting it to handle steam?

Thanks!!

Unknown

adding two words

Everything what Mr Brad White said is correct..... I'm adding three words...
Weil McLain boiler
With ANY boiler comapny... Must follows the piping instructions to the detail or you will have problems....

Jeff_66

clarify?

Thanks for your response but we're not sure what you meant by your message referring to adding 3 words. Did you mean that Weil-McLain boilers are good?

Jeff_66

questions

Thanks for your reply but please bear with us because we are not experts and are not clear on some of your language. In a nutshell, the square footage of radiation (calculated by adding the square footage from each radiator in the house) has been calculated by 3 people and each time has come out around 750. According to 2 contractors, this square footage requires a 300,000 BTU boiler. I'm not sure about the rest of your reply (having to do with piping, etc.).

Brad White_165

Boiler Trim

It would seem that the EDR you had calculated is a good number, Jeff. Glad to hear that much.

All steam boilers are selected on EDR the ability of the boiler to produce steam.

The boiler trim I was referring to are the operating controls and near-boiler piping which are essential and specific to each type, steam for one, water for the other. Within those and especially for steam, the manufacturer's recommendations (requirements really) should be followed to the letter.

Jeff_66

OK...

Thanks! We've received one quote from a local heating guy with a very good rep. He sells Weil-McClain but the 300,000 size has no vent damper. I'll try to find the thread you referred to about dampers.

Jeff_66

another question

Hi Brad (again),
What does the IBR rating refer to?

I did read through some of the posts about dampers but as you know, much of the debate was rather technical. Basically, we have a 400,000 BTU boiler that is only 4 years old and was installed incorrectly by the previous owners (which caused the demise of the boiler). Since we're spending an arm and a leg for a new boiler, we're trying to figure out every way possible to earn back at least the arm in future fuel savings.

I know a bit about steam systems from reading this page over time, but I don't expect to be able to develop much more expertise before we need to decide on a new boiler (which is imminent). We just want to gather whatever info we can to make the best immediate decision we can. On that note, we REALLY appreciate your help!