Heating an Old House: Gas Heat Options

ILikeEmOlder

1700s house in climate zone 6. Gut rehab began in 2021. Current heatload of the building is 70K Btu (conservatively speaking).

Current heating setup is 60K Btu mod-con combi boiler (in the cellar) feeding staple-up plated radiant tubing for the 1st story; 120K Btu 2-stage furnace (in a conditioned attic) serving 2nd story and attic spaces. Furnace was installed in 2021 to serve the entire house when heatload was just about 130K Btu. Combi boiler went operational about a week ago.

I am between the following options for dealing with the existing furnace. Option 1: Replace existing furnace with 60K Btu modulating furnace. Option 2: Keep existing furnace (as emergency heat source), and add 40K Btu hydronic air handler. Option 3: Replace existing furnace with mod-con boiler connected to a hydronic air handler.

Thoughts?

mattmia2

It all depends on what you want to spend and how the existing work is done. If you extend the existing ductwork to the 1st floor the ac will never be even between the floors unless you zone it. You could add ac to the first floor. You could add a hydroair coil to the existing furnace and control the blower to heat the second floor off the boiler. You could add hydronic emitters to the second floor and add either mini split or ducted ac to the first floor with a separate system. There are lots of options.

Jamie Hall

Has the staple up radiant in the first floor been even remotely adequate?

It appears from the list of options (which is certainly not the whole spectrum of possibilities!) that you are leaning towards forced air heat as the main heat source, with the radiant possibly for warm toes. Would that be a correct assumption?

HVACNUT

https://forum.heatinghelp.com/discussion/comment/1838372#Comment_1838372

I think the best option went to the scrap yard during the demo.

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1838451#Comment_1838451

Well, yes. But as in so many situations, the "junk it, it's old" philosophy rules. It is what it is, and now the OP needs to pick up the pieces.

ILikeEmOlder

Jamie,

The staple-up radiant is doing a pretty darn good job, even with the near zero temps we’ve been seeing over the last few weeks. I set the SWT to 130F for all but the coldest days, and it is keeping the 1st story comfortable at 66F.

I’m leaning towards forced air for the 2nd story mainly because of practicality and secondly for aesthetics. The practicality side is real. The original structure is traditional mortise and tenon timber frame, so there is no real way to get tubing to wall-mounted rads, otherwise I would have preferred a radiant option for the 2nd story.

ILikeEmOlder

Matt,

Fortunately the house only needs AC in the 2nd story, this is one of the main reasons why I chose a ducted setup for the 2nd story.

In an effort to keep it simple, I had hoped to use the existing ductwork (in the attic) with minor mods. I am ready to focus on a heating-only setup for a few years (leaving AC to be dealt with down the road).

My trusted HVAC guy is dead-set on scrapping the furnace and going with a ducted Mitsubishi mini split for the 2nd story. Inverter drive with HyperHeat is a great way to go, but the price tag is steep (at this point), and new ductwork would be required.

ILikeEmOlder

HVACnut,

Care to explain what you mean by “I think the best option went to the scrap yard during the demo?’’

pecmsg

https://forum.heatinghelp.com/discussion/comment/1838702#Comment_1838702

What was there before demolation?

Jamie Hall

Yes, if it's post and beam running piping in the wall is a practical impossibily. However, may I point out that in the restoration business — not the gut and rehab with drywall or some such travesty — the accepted and normal way of running either steam or hot water heat is carefully and neatly run pipes visible in the rooms they go through. This is an honest statement of what was done to bring the house to more modern conditions without fakery. This is also done when adding a bathroom on an upper floor — although there it is more common to enclose the pipes with a well-crafted wooden chase to match the existing trim.

ILikeEmOlder

pecmsg,

I inherited a beast of a furnace, and some nasty ductwork (only serving the 1st story). No heat source whatsoever for the 2nd story.

The picture gives you an idea of what I inherited with this house. I was an especially huge fan of the water heater in the kitchen 😉

mattmia2

water heaters in the kitchen were once pretty common because the cookstove used to have a range boiler on it and when they got rid of that the piping for the water heater and the vent was right there.

ILikeEmOlder

Jamie,

I would have loved to restore such a house, but too much **** had taken place over the decades in this house.

I am a carpenter by trade, and I have put thousands into repairing, replacing and adding structural elements where previous renovations had gone wrong.

I’m past the worst, and now I have to thread the needle of keeping original character while adding modern HVAC systems.

Jamie Hall

That happens. Not to worry — do the best you can with what you have! I've seen some really creative modern work — honestly expressed as such — in old (like — really old) houses.

Intplm.

@ILikeEmOlder

This is a very charming nice looking house you have. The front looks great and from what I can tell it will even look better as you continue. I especially like the kitchen. I truly do, right down to the dog. I hope in the future you will post some before and after pics.

psb75

I agree with Intplm. But it doesn't look like 1700's vintage from the outside. Maybe very late century? 1800's modifications may have happened.

ILikeEmOlder

psb75,

Right on the money. 1800s mods (including the porch and the front gable). The roof was pitched from something like a 6:12 to a 10:12 (to accommodate the 1800s addiiton).

tim smith

What about a heat pump for 2nd floor with possibly, probably some supplemental heat & then the radiant for main floor. The supplemental heat could even be a water coil in duct off boiler if you like. Or maybe the #s work for heat pump only but based on your climate zone, heat pump could come up short some of time. Depends where you actually are on map and how well insulated you will be.

Good luck