Central Boiler Classic Edge 350 piping sizing

sony224422

I figure people here are a lot smarter than I am

I have gained access to a functioning CB edge 350 and i am doing as much research as i can before i commit to anything. I know the furnace is in good working order with no leaks, and holds roughly 200 gallons of water. I see it has a max BTU of 178k. I see a lot of back and forth on what size thermopex to use- 1 inch or 1.25 inch and that is determined by the pump size and btu load. 

I haven't decided how far i'd be with putting the boiler somewhere, but doing some measurements i know i will be no farther than 125 feet to the house. from the house inside, it would be about 10 feet to the DWH plate (20 plate 40k btu) and then another 25 feet to the WTAHX (160k btu) for the forced hot air. I know that i am not going to be using or hitting the 200k btu load, as i do not believe the furnace can produce the 160k anyways, it’s an oil fired 104k model. I am heating a 1700 sq ft house build (around 2300 sq living area) in the 1940's with poor insulation (for now) in half the house. I burn roughly 600-700 gallons of oil a heating year.

I may want to in the future add radiant floor heating for the basement and first floor when/if i ever get the time, but it is not on my priority list at the moment. 

Any suggestions on piping size into the house? My thoughts are go to 1.25 but i don't want to be oversized either if i don't need to be. 

An additional thought- if i bring 1.25 into the house, everything else has 1 inch or smaller fittings on it, does that impact anything? I know for the radiant or any other zones i'd be using a zone valve and additional pumps, but the main loop would be the plate exchanger and the WTAHX.

Jamie Hall

For that long a run — 250 feet at least out and back — I'd go with at least inch and quarter. Maybe even inch and a half. It's head loss you're looking at, and keeping the pump size reasonable.

And insulate it.

And no, dropping to smaller sizes inside the house isn't going to be a problem.

hot_rod

If you want the full output, 170,000 btu/hr or so, to the building, then you need to size the pipe accordingly.

So you next need to know the distance.

Here is the 250' result from the calculator at the PPI website for 1-1/4 and 1-1/2" Notice the head loss difference, as @Jamie Hall mentioned.

I would first want to know how many BTU/hr you actually need to deliver. Could be that boiler is twice the size you need? Is this to heat just one building?

The only way to get you a good answer is to have you or someone do a heatload calculation. Then you can make the best tube size decision.

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ScottSecor

Saw your post on THT. I agree with Jamie, 1.25" pipe at minimum. May cost you a few dollars more for 1.5" but you likely only will do this work one time. Keep in mind with larger pipe (tubing) you reduce the friction of the pipe, often allowing for a smaller pump (and less electricity draw).

I did not notice where this home is located (climate area), I assume your in a rural area with free or almost free firewood. The reason I mention this, is we normally base main trunk pipe sizes on load (heat loss) and length. You mentioned the total square feet of heating space will be 2300 square feet. In some areas this could be as little as 23,000 BTU in the dead of winter and in bitter cold areas this could require as much as 125,000 BTU.

sony224422

thank you everyone for the comments!

I was thinking I would want 1.25, 1.5 hadn’t really crossed my mind as I haven’t seen any insulated pipe that big. The connections on the back of the boiler are 1.25

I am in located in middlesex county Connecticut, about 10 miles from the shore. Our winters vary- sometimes mild sometimes below freezing. Our hot air was installed after the house was built, and the ductwork is lacking. My goal is to eventually move to radiant floor and baseboard or add additional ductwork.

Is there a heat loss calculator or is it more of an on site type deal? The whole front of my house has little to no insulation which I have been doing as windows are replaced and siding replaced. It is 2x4 walls, though true 2x4 which allows a tad more insulation

EBEBRATT-Ed

With that length of run I would use 1 1/2. Your close to the max flow on 1 1/4 even on a short run

sony224422

not arguing- just curious why are so many undersized at 1 inch?

I forgot to mention that this would be heating my house and if I ever closed off my attached garage that is not likely

leonz

Good morning,

You may want to seriously consider selling your central boiler and installing an outdoor coal stoker boiler or a coal stoker boiler in a small shed to burn Anthracite Pea Coal instead. You would have much less work amd you would be able to buy coal for fuel once per year or less and also heat your domestic hot water with a plate heat exchanger with the pex pipe entering the home.

You will have a boiler that has a closed system that will create much more heat for you per hour and have zero smoke to deal with and not upset your neighbors with smoke from an idling boiler.

You would be able to use twin pipe 3/4" oxygen barrier pex tubing in a closed cell foam in 4 inch solid drainage pipe and only have heat loss of 1 degree per one hundred feet and have quicker heat recovery. You would also be able to use salvaged hot water radiators to create even more thermal mass to heat your home.

I am sending you a PM

hot_rod

how many square feet is the home? That will allow you to ballpark a heat load number. If you are continuously upgrading, the heatloss number will go down

Also I suspect that btu output number on the heater would be at a full fire condition, which is not to realistic

To those that pipe witb 1”, they probably get 80,000 btu/hr to the load. Whether they know it or not

@groundup is the resident expert on theses systems, he will have realistic numbers to share

sony224422

my floor plan is 1700 sq feet but would heat second floor and basement as well which I believe is around 2300 combined

hot_rod

So a good chance the entire load is 2300 X 25 btu/ sq ft= 60,000 or less. Just a WAG