Completely new system build in a gutted old house. Help?

Landlord_contractor

Hi all, looking for any advise or commentary you might be able to throw my way on this derelict project house I'm working on that's honestly not a great house, in a pretty poor area that I'm doing on a shoestring budget to be a rental.

The house is about 1,300 square feet two story Craftsman/bungalow, main front room + dining room + small kitchen and bath on the first floor and three bedrooms on the second floor built sometime in the 1920's here in near-central Ohio.
The house has NEVER had a central heat system. Ever. It was built with a heating stove in the living room and and cookstove in the kitchen that shared a common chimney and that's the only heat the house has ever had.

The house is built rather... squirrely... where due to the center beams and the odd sill plate I can't really get air ducting in the walls, so I decided on boiler heat with baseboards

I bought a pallet of miscellaneous 20 or 30 Slant/Fin baseboards, Beacon Morris toekick heaters and other hydronic parts, pumps, etc. for practically nothing at a surplus auction and from a duplex that was being town down I got a 3 year old Lochinvar Solution Plus 135,000btu boiler and a 5 year old Laars Minitherm 65,000 btu boiler. So I think I have all the bits and bobs to make a full system.

Now the piping plan is where I've confused myself as I honestly don't know whether I should do monoflow, 2 pipe straight return or 2 pipe reverse return or home run.
With the idea of a 2 pipe system I think I could just run the 2 pipes down the length of the center beam in the basement and 'TEE' off from that.
But the idea of a monoflow loop also seems to be valid as the house is basically 24' x 22' square where I can have the baseboards in the rooms and then just connect to the loop with short runs of 1/2" pipe
Home Run seems great if I were trying to zone separately, but I'm considering this house 1 zone.

I also figure I'll be using the Laars boiler as it's size seems better suited to the house btu needs, but it's a low mass boiler and then with baseboards... that's not a lot of water in the system, so should I add some sort of buffer tank to add water mass to keep the boiler from cycling?
I was thinking I could use a 20 or 30 gallon electric water heater repurposed as a buffer tank to add more mass of water to the system.

Any advise would be greatly appreciated.

Jamie Hall

Nothing like a clean slate, eh?

My preference for the system -- others may differ -- would be a parallel flow system, with the two lines running down that centre beam as you suggest. Then your radiation could take off from them -- again as you suggest -- with simple T fittings. I dare say you could run a branch off the feed and return to the second floor up by the chimney, and branch from there for those to the respective rooms.

Before you start laying pipe, though, go to a good heat load calculating program (I like this one: https://www.slantfin.com/slantfin-heat-loss-calculator/ ,but there are others) and determine the heat load for the entire house and for each room. The program I mentioned will even give you the amount of baseboard you need for each space.

I would use a generous pipe size for the main and return trunks. That will aid balancing the system.

Then you will have a very good idea of what needs to go where, and that will simplify balancing and adjusting the system later. To aid in balancing, I think I would place a valve on each line where it takes off from the feed, down in the basement, and use that. That way the tenants won't be quite as likely to upset things once you get them dialed in.

That program will also give you the total heating demand for the house, which you can use to decide which of your boilers to put in. If the smaller one is adequate, I'd use it, but I'd suggest that you not undersize even a little, as tenants can get fractious if they feel there isn't enough heat. The Laars should be fine on one zone, so long as it meets the requirement.

Both of those boilers are atmospheric type. How is the chimney? You may find that it needs to be lined.

Ironman

With that small of a foot print, I think that I’d just run a series loop. You could run the supply down the middle and split in both directions for a better balanced system.

JUGHNE

Have you considered 2 zones, top floor and main floor?
Top floor usually ends up too warm with one system.

Gilmorrie

Those boilers are way, way oversized. For such a tiny space, I would consider electric baseboards, and have the renter pay for power. Let him decide how much heat to use.

EBEBRATT-Ed

@Landlord_contractor

I would do 2 zones 1st and 2d floor. Run 3 pipes down the middle common return and a first floor supply and a second floor supply. Use pex off the mains to save money. 2 pipe direct return is fine for a small job. 1 circ pump and 2 zone valves (unless you have another pump lying around. Do a heat loss and size it right and you will be fine.

I don't see a need for a buffer tank

JakeCK

Gilmorrie said:

Those boilers are way, way oversized. For such a tiny space, I would consider electric baseboards, and have the renter pay for power. Let him decide how much heat to use.

That is a horrible way to treat renters... They'll have electric bills nearly as high as the rent in winter.

That 65k btu boiler isn't too far off for a 1300sq ft old drafty house. It would be a perfect match for my 1928 sears kit home as it stands today @ 1478sqft. Sure he's got it gutted so he can probably cut the heat loss down to 30-40k btuh on a design day but at the end of the day he's building it as a rental so its going to have 2x4 walls, most probably under insulated attic and less than perfect air sealing.

edit: The more I think about that sentiment the more it sounds like a bad idea. What if the renters decided they don't want to pay for the bill and dip out leaving the owner holding the bag? Or worse what if they decide to just turn it off and use kerosene heaters or some other equally dangerous source? What if they let the house get cold and all the pipes freeze. Nah I'd rather make the house comfortable and affordable for the tenants less likely they'll mess around and screw one over. And all electric heat will require a service upgrade to at least 200amps. Just my 2 cents.

JakeCK

Also this house sounds like a fun project. Just saying.

hot_rod

What about cooling?  Maybe a mini split with multiple heads, that would be the lowest operating cost also, perhaps