Vitoden 200 8-32 or Solo 110or175 Boiler

brad_14

Trying to decide on a boiler for new construction. 1860 Rancher with walkout basement and 700 garage in Northern British Columbia (we can get a cold winter -40 for 2 weeks in Jan but for the most part 0f) The heat calc my supplier ran estimates 112k BTU requirement.

I have just laid my basement slab tubing ended up with 1750' of pipe 2 zones bathrooms, mudroom 6" spacing also first 3 loops around perimeter. Everywhere else 12" spacing with 1/2" pex.

Upstairs it will be in joist stapleup 1860sq'. Garage is 700sq'but will be heated to an absolute min(keep above freezing). House has R22 mineral fiber with R5 ridgid foam on exterior with Hardiplank. Attic R50 cellulous, Argon low-e windows, fibreglass doors generally a tight low loss house.

I am undecided between a viessmann vitoden 200 8-32 or 11-44 or a triangletube solo 110 or 175. I have the 2 different radiant temps and would like indirrect DHW. Solo would be simpler to vent and cheeper. Would both operate with simular efficeincy given my use. Viessmann will cost me $2500+ extra for sure. Worst thing about Viessmann is the exra cost in venting.

Would you go with the slightly undersized unit 8-32 or 110, I'm leaning this way. I have read that 25% undersizing in a tight house seems like a no brainer, True?

We have a 61KBtu Harmon Pellet burner on the main. We are a family of 4 and our washing machine does have an inline heater so DHW is not a huge deal.

What about manifolds for my basement slab I am thinking I just need ones with isolation/balancing valves maybe slant fin. I see the wirsobo ones but they are $$ and if i'm going to dump extra money I would rather on a good boiler.

What do you think? What would you install in this situation? Somthing else?

brad_14

Vitoden 200 8-32or11-44or Solo 110or175 Boiler

Trying to decide on a boiler for new construction. 1860 Rancher with walkout basement and 700 garage in Northern British Columbia (we can get a cold winter -40 for 2 weeks in Jan but for the most part 0f) The heat calc my supplier ran estimates 112k BTU requirement.

I have just laid my basement slab tubing ended up with 1750' of pipe 2 zones bathrooms, mudroom 6" spacing also first 3 loops around perimeter. Everywhere else 12" spacing with 1/2" pex.

Upstairs it will be in joist stapleup 1860sq'. Garage is 700sq'but will be heated to an absolute min(keep above freezing). House has R22 mineral fiber with R5 ridgid foam on exterior with Hardiplank. Attic R50 cellulous, Argon low-e windows, fibreglass doors generally a tight low loss house. We also have a 61KBtu Harmon Pellet burner on the main.

I am undecided between a viessmann vitoden 200 8-32 or 11-44 or a triangletube solo 110 or 175. I have the 2 different radiant temps and would like indirrect DHW. Solo would be simpler to vent and cheeper. Would both operate with simular efficeincy given my use. Viessmann will cost me $3000+ extra for sure. Worst thing about Viessmann is the exra cost in venting.

Would you go with the slightly undersized unit 8-32 or 110, I'm leaning this way. I have read that 20% undersizing on an above average house is a no brainer, True?

We are a family of 4 and our washing machine does have an inline heater so DHW is not a huge deal.

What about manifolds for my basement slab I am thinking I just need ones with isolation/balancing valves maybe slant fin. I see the wirsobo ones but they are $$ and if i'm going to dump extra money I would rather on a good boiler.

What do you think? What would you install in this situation Viessmann or triangletube and undersized or not? Somthing else?

ALH_4

Based on

Based on the info you have provided, I would say the 8/32, 110 is the way to go. It's a big price jump to the 11/44. If it comes down to it, I would use extruded plates for your radiant instead of the staple-up and use the Prestige. Then you dont need two temperatures. Your manifold choice depends on your zoning. Or you could even skip the radiant on the 2nd floor and use TRV'ed radiators which saves quite a bit of money unless you're installing your own radiant floor. Labor is the big difference. A nice system could be radiant in the bathroom and kitchen with radiators everywhere else upstairs. There are a lot of options to keep costs down so you can put more money into the boiler and manifolds.

-Andrew

Constantin

Since you plan on having a pellet stove...

... I would consider going with the smaller size. The stove would put you easily over the worst dip in temperatures, more than the 10kBTU deficit that you may or may not have, depending on the mass of the home, insolation, etc.

Since you've done the input for the calculations, I would adjust the indoor temp in the heat loss program down to the point where the boiler output would be able to match the load for a given return temp (remember, staple-up tends to run hot and very hot return temp water reduces the net output of a condensing boiler). Once the output matches the loss, you'll know the minimum temp the boiler will be able to maintain even if the pellet stove is not working (i.e. you're on vacation, for example).

As Andrew suggested, extruded plates would help by allowing you to run lower water temperatures. That in turn will boost the output of the boiler (lower return water temps = more net output).

if oversizing via Manual J is a concern, then stick to the ASHRAE 2% numbers, not the lowest temperature you can locally experience. Going with 2% design day conditions allegedly cancels out any "extra" the heat loss calc padding.

One concern is to ensure that your 1/2" tubing loop lengths are not longer than 300' and that they're all about the same length - that makes balancing easier. Zoning them by room is a great idea, if practicable.

Considering the Δ$ between electricity here and the cost of raw fuel, I would not have the washers cook the water for me... I'd use an indirect water heater for that. But all conditions are local.... for all I know you're enjoying hydro power at $0.04/kWh.

One thing that concerns me is a garage that is heated to the minimum possible. If pipes and other hydronic items are installed in/near that space, you won't have a lot of margin before they may start to freeze up. Most contractors here would probably isolate and use glycol in the RFH loops for that space also.

My mum had some pipes freeze in her basement because of a very small crack in the wall that blew cold air on a pipe... in a normally 55°F basement. Because of the extreme cold (and the boneheaded omission of heating in that room) the temp there was in the 40's... so, think a bit about how to ensure that all the pipes that run above and around the garage will stay warm if -40°F is in the cards.

brad_14

more details

Thanks both of you you have both provided usfull info.

In the basement I only have 2 zones (I did the layout and install) would have been nice to break it up more but I Think it will be acceptable. On zone one my loops are 248'min and 268'max zone 2 loops are 230'min 240'max.

Extruded plates seem like an excellent solution. The second floor surfaces are going to be Bamboo & Tile. Do you think there is any advantage using Pex-al-Pex to? I will insulate joist cavity with R22 mineral fibre. With all that do you think I can make it work on one temp?

I am doing all the pex work.

Well I gotta go to work.
thanks again

Nick S

60 BTU/SQ.FT?

What is your design temp? Your heat loss sounds pretty high for a 1860 sq. ft ranch, even if your design temp is -40*. I could be wrong, but you may want to double check those calculations.

brad_14

Heatloss

I believe the slab design temp is 118(i'm at work and don't have it with me)

I should qualify that 1860sq' that's main floor + Basement + Garage so it's closer to 30 BTU/sq'.

ALH_4

More

Generally in basements you can reduce the heat load when compared to an above-ground floor. You may be able to get away with a 6-24 Vitodens.

Here is why I probably would use an 8-32:

There is not a lot of price difference between an 8-32 and a 6-24, and an 8-32 will heat up your indirect more quickly. Also the difference between the low side of the 8-32 and the 6-24 shows that at low fire there is a mere 7,000 btu/h difference between the two. At high fire there is around 27,000 btu/h difference. Modulating boilers are more efficient at lower firing rates, so using the 8-32 will keep the boiler more efficient. Will the boiler short-cycle at low fire? This is where the rest of the system can make a difference. You want to have the boiler set in a way that will work with the system. If the reset curve is set too high, the boiler will sit there and circulate warm water through the pipes in the mechanical room while none of your zones are calling for heat. If you learn to adjust your own heating curve you can fine tune this. I recommend every homeowner with a reset control learn to do this.

Once you have the boiler set to work with the system and the heat loss, ideally at least one zone valve will be open at all times. This will be the zone with the highest heat load per unit area. The great advantage of these modulating condensing boilers is that they can be set to work in concert with the rest of the system. The Vitodens has an excellent control with a lot of adjustment built in.

-Andrew