How to downsize a boiler.

fabaze12

I have a 3 family, 2600 square feet house in Massachusetts.

One steam boiler (Weil-McLain A/B-SGO-7(W), 242k BTU), feeding mostly 1st and 2nd floors. Third floor unit only has one radiator and they use mostly electric baseboard heat.

I would like to separate the heating utilities and I was wondering if a smaller, properly sized boiler feeding the second floor only would be an issue with the current steam mains or if that would be a problem for the smaller boiler.

Hopefully I've given enough information.

Thanks.

Fabiano.

ethicalpaul

No but it could be a problem for the larger existing boiler. It will suddenly be even more oversized than it probably already is.

Plus the first floor tenant is going to be paying to heat the upstairs tenant, but that's outside the scope of your question and not related to steam heat.

fabaze12

@ethicalpaul, I was thinking of leaving second with steam heat. Just didn't know if a smaller boiler would suffer with the existing steam mains.

For the first floor, I was going to do heat pumps. Not only to have separate utilities but also to heat the unit better.  No heat in kitchen and it's very uncomfortable I'm winter. No hear in rear entrance/mudroom and it's freezing cold in the winter. Notva properly planned house when it came to heating amongst other things. 

mattmia2

It would almost certainly be far less expensive to get 2 salvaged radiators and put them in the unheated spaces assuming you have access from below.

ethicalpaul

Oh I see, I thought you were leaving steam on both. 

To answer your question, no, the boiler won’t mind the existing main, especially if it’s insulated. But even without it there’s plenty of extra capacity in a boiler sized via sq ft of steam.

but I’m curious, will it be central heat pump with ducts or a head unit in each room, or what?

fabaze12

@ethicalpaul head units in each room.

I'm just trying to find a feasible solution to have separate utilities by keeping steam for one apartment and doing the heat pumps with head units in each room in the second apartment.

fabaze12

@mattmia2 , I paid $8,000 in heating oil this year. About $6,000 per year for the past 2 years. So that's about 20k!? I have a family member that paid around 30k to upgrade his house from hot water to heat pumps. So in about 2 years his upgrade will be cheaper than my heating oil for as long as I own the house and will only go up. 

May be cheaper in the short run to add 2 radiators....

pecmsg

And that steamer will last 20, 30 years. The heat pumps 7 1/2 to 12 years IF installed and maintained properly by qualified personnel!
calmer, I put heat pumps in my own house for the shoulder seasons. Once he gets to 20° outside, I 
switch over to the boiler!

Kickstand55

Seems like you have many options to make changes. The steam guys may grimace at this, (I do steam too), but whereas there are tenants involved, I would consider forced hot water with separate boilers for each unit to include an indirect hot water heater for each. Maybe even gas fired. The first floor could have a hot water air handler with a/c. That is, if there's enough money to do it and depending how long you plan on living there.
Maybe one unit at a time may work.
Best to contact a very reputable contractor knowledgeable in steam and fhw as well as hvac.
Do your homework, check with an engineer or architect. Oh, and insulate, insulate, insulate. The money well spent is worth it.