Converting 2 Family with multiple heating types

obos

Looking for some general advice as I start to think about replacing my heating setup. We bought a 1890's house over the winter, and managed to get through the winter with only a couple breakdowns, and as weather gets warmer we are looking to replace before next winter.

The house was once used as a 2 family and has a bit of an odd setup which has me puzzling a bit about the best direction to take. There is forced water baseboard radiators on the first floor. However, the 2nd/3rd floor are forced air.

The first floor has a gas boiler (Hydro-Therm of unknown age, guessing 70's) and standalone gas water heater (GE tank). The 2nd floor has a gas Ruud furnace from 1969, and another standalone gas water heater (Whirlpool tank).

To frame this: For a variety of reasons, the intent is to convert this 2-family into a single. We also intend to be here a long time. I know we want to add AC, and I know we should get to a single hot water heater efficiency wise. The question is what to do about the boiler and furnace. The house is about 2400 sq feet counting the attic. Most of it is not insulated, but the plan is to add blown in cellulose with the help of a local utility.

I had an informal discussion (not a detailed bid) from a plumber I've worked with before who suggested getting a new high efficiency boiler with zoning to do forced water heat on the 1st floor and a Hydro Air coil zone to replace the furnace and provide heat upstairs. He indicated you can get a coil with AC loop as well to easily tie that in. (We did not specifically discuss, but expect this setup would also involve a indirect hot water tank on the boiler). I don't know a lot about the Hydro Air coil -- it seems like a decent enough idea, but my research suggests varied opinions on it.

Another thought would be to go entirely forced air. The ducting exists only to the 2nd/3rd floor (semi-finished attic) now, but likely would need to be replaced due to it's condition anyway--so likely a cost I'm in for regardless. The 1st floor already has grates everywhere -- it clearly was forced air once upon a time. This would have the side benefit of getting AC everywhere easily.

Correct me if I'm wrong, but I don't expect there is an argument to maintaining two separate systems (i.e. replace both furnace and boiler, leave setup more or less as is). I know I'd likely get more in rebates from local utilities this way, but expect long term efficiency and run costs wouldn't bear out.

I'm just starting to reach out and get some bids but appreciate any guidance as the mixed heating types have me a bit puzzled.

EBEBRATT-Ed

My guess is originally both floors were gravity hot air coal fired.

Not crazy about hydro air and most on this site will probably recommend two zones or more of hot water heat, 1 boiler and an indirect hot water tank.

This will in my opinion be more comfortable than an air system.

Depends in part on what shape the first floor HW system is in. Are the baseboard and piping suitable for reuse?

Air conditioning could be ductless splits or central air as you already have duct openings to the second floor and adding ductwork for the first floor wouldn't be an issue.

depends how much you want to spend. You get what you pay for.

A qualified installer is the FIRST thing you need

JUGHNE

How about pictures of existing systems?
Boiler, piping, old air grills in walls & floors, and 2nd floor furnace and ductwork.

obos

Here are some photos of the hardware.
Furnace is a Ruud LR-175GB. Looked up serial, believe its from 1969.


Furnace and water heater for 2nd floor


Some of the duct work.


Here is an example of the floor outlet. There is one of these per room for the most part. They are not necessarily on outer walls.



Boiler is a Hydro Therm HC-85C(?). Not sure of age. 70's?

Boiler and water heater for 1st floor. This is on the other side of the wall from furnace--chimney in between.


I did not take a picture of the baseboard radiators but they should be good for reuse--they are probably from 1970's, seem to be decent shape, all copper pipe.

obos

I had an HVAC guy out this morning for my first quote. Said ducting could potentially be reused for heating, but if I want AC they will have to update the ducting to 2nd/3rd floor to get an insulated product, else I'll get condensation and mold. Said my ducting looking like '60's. Replacing that ducting means opening walls, so not cheap. I was honestly not expecting that ducting to be useable for anything, but opening up a lot of plaster and lath walls doesn't sound fun.

He was also going to work up numbers on ductless mini-splits, bu his concern there was the number of units needed. (I also know I'm going to have issues with the wife on those appearance wise, but worth talking about...)

We very briefly talked about a mix of mini-split and forced air but he didn't seem to think it was a good path with my setup.

obos

Looking into solutions to do ducting without ripping out walls/floors, the only thing I'm coming up with are mini splits and high velocity small-duct systems.

The mini-splits quote was quite high (as predicted, due the amount of equipment and rebates tapping out after a couple units).

What are the thoughts about high velocity small-duct systems?

Would like to do this once and get AC at the same time if we can...

obos

2nd contractor out to look, his first thought was a boiler and hydronic coil (hydro air) for the upper floors. Was not sure a furnace/forced air everywhere would work as it may be too much for one furnace.

Interestingly, he said you could add AC with the existing ducts. He said you will lose a bit of efficiency with them not be insulated, but did not seem concerned about condensation etc. as they are all interior wall runs. So now I have one contractor who said they won't do AC with the ducts and one who will. Any thoughts?

gschallert

Personally I wouldn't use the existing ductwork unless it matched the specs of a manual J & CFM per room. Did either of the contractors do a heating or cooling load calc?

You mentioned you were planning on being in this home a long time. If that is true I would strongly encourage you to think long term and not just settle for the quickest cheapest route. If cost means you can't do heat & A/C at the same time there's nothing wrong with that.

Without knowing the floorplan, if it were me I'd make every effort to get a second hydronic zone to that 2/3 floor. I'd go with the mini-duct or ductless mini-split for A/C (with heatpump for shoulder/backup heating if in cold climate), again determined by structural layout. Based on quotes I got last year, I don't know that the HV mini duct system will be any cheaper for you than than the mini-split. They are perfectly good solutions though.

What architectural style is the home? American Foursquare, Victorian?

JUGHNE

Often with old gravity systems the second floor was supplied by wall stack duct installed between studs of the inside walls. Might be only 3.25" X 14" per run. You can blast heat upstairs with these with a 8" round supply connected in the basement, but probably not cooling. The few I have seen use the stairwell or floor/ceiling transfer grates for return air.

obos

I am in Massachusetts.

It's a colonial revival, 1890 construction. House floor plan is nearly square, rough layout is center stair case (running side to side, aligned somewhat to one edge) with 1-2 rooms in front of stair, 2 behind. 3rd floor (attic) has crawlspaces each side (running front to back), with 2 rooms (one in front, one behind stair). Overall about 2300 sq ft with attic.

Between the 2 houses I've owned, I've had about 7 plumbers or HVAC guys out, ZERO have ever done a heat load calc. I've asked a couple times and have been told they will do it before install not but not at the estimate stage. FWIW I did not actually get past estimates stage in my last house, numbers (and time remaining there) didn't add up.

I am missing my old cast iron radiators, but we really want AC and the house is already setup for forced air for the most part, so plumbing the rest of the house for hydronic doesn't seem cost effective. We also have some renovations in mind down the line, but they are years out, financially. Would wait to do HVAC if we could, but our units are so old, I'm not confident that is a good path.

obos

JUGHNE said:

Often with old gravity systems the second floor was supplied by wall stack duct installed between studs of the inside walls. Might be only 3.25" X 14" per run. You can blast heat upstairs with these with a 8" round supply connected in the basement, but probably not cooling. The few I have seen use the stairwell or floor/ceiling transfer grates for return air.

This is the only return I'm aware of, near base of first floor staircase:


I have been told that is likely insufficient.

The feeds going upstairs are all round galvanized such as below. Some run up a wet wall in the back of the house, the rest run up next to the chimney on the other side. 7 of them, IIRC. I have not measured but 8" sounds about right.

Jamie Hall

Where in Massachusetts? If it's somewhere central, try @GW (Gary Wilson) in Northhampton or @Charlie from wmass in Springfield. Both top notch men.

obos

Jamie Hall said:

Where in Massachusetts? If it's somewhere central, try @GW (Gary Wilson) in Northhampton or @Charlie from wmass in Springfield. Both top notch men.

I'm in Salem, so probably too far from them. Thanks though

gschallert

obos said:

I am missing my old cast iron radiators, but we really want AC and the house is already setup for forced air for the most part, so plumbing the rest of the house for hydronic doesn't seem cost effective.

That's just it, I don't think the house is "already setup for forced air for the most part." I think you're quite a long ways from a balanced forced air system. You might be able to squeak by with what you have for heating the upper floors but as @JUGHNE mentioned, I don't think it's going to cut it for A/C.

Box style should allow for a second hot water zone to be piped up easy enough and me personally, I'd run baseboard around the entire perimeter, as much more as I could squeeze in to give me excess emitter capacity so I could run lower supply temps and condense.

You can do a manual J/D yourself if you have the ambition, it's something I would definitely recommend to any homeowner so you can gauge whether what is being quoted to you is appropriately sized or not. You definitely don't want to oversize a central A/C unit for many reasons (mold included) and right sizing a heating and domestic hot water solution will save you energy costs in the long run. Check out the find a contractor section here:
https://heatinghelp.com/find-a-contractor/

Scott Milne is in Manchester so perhaps you're close enough to his service area.

GW

Yes thanks too far away for me,

Good luck with that project

tim smith

I kind of like the idea of Hydro air for 2nd and 3rd fed from attic and radiators on main floor. Are you not ducting main floor? I did not see that you have or were ducting it? Radiators on the main floor. All fed from condensing boiler with an indirect water heater. Pretty good system. Now if you want a/c main floor you might just scrap the wet side totally as it may not make sense with a budget.