Boiler desicsions

[Cookieman]

I am looking for some ideas on the best boiler to do a multi option heat system. I'm currently building a 2700sq ft. house in Anchorage. I've done a quick heat loss calc and near as I can tell I need about 50,ooo btus per hour. The system will have a tri tube smart 60 water heater, along with over the floor radiant, hydronic unit heaters for the garage and small portion of radiators for the great room which has 20' ceilings. I have been eyeballing the gv90 series by WM for the cast iron heat exchanger, but since I am going to be condensing anyway would it be better to just go with a mod con? I know there are a bunch of different heat ranges in there 180 for the rads and unit heaters and probably 130-140 for the radiant. I'm trying to keep the boiler as simple as I can, however its not cost effective for me to put in a chase or chimney. Any suggestions?

 

[Dana]

The direct vented Burnham ESC3-3 or ESC-4 would do OK if natural gas is cheap and you don't want to go with a mod-con. If the 50K heat load was done using I=B=R calculation methods the -3 would still have some margin, but if it was an aggressive Manual-J stick with the -4.

The ESC series is tolerant of water temps as cool as 110F without needing bypass plumbing, which may make the system design easier.

The HTP Versa (either the Hydro or Flame) combi would also cut it, and you can skip the Smart 60 indirect. They're fairly easy to design a system around too, and have the advantages of modulation and condensing efficiency.

 

[Sponsor]

 

[BadgerBoilerMN]

I would not make this decision without an experienced review of you floor plan. It is rare when supplemental heating is needed with radiant floors unless the construction is old, bad or the floor to glass ratio is large. The volume of the room is but one factor in the heat load, far less than for cooling.

Domestic hot water demand is best determined by loads and combi systems such as the VersaHydro Dana suggests are brilliant in properly sized, installed, programmed and maintained. If the master tub exceeds 60 gallons and you have a 25 gpm tub filler, the Versa my let you down.

I can never see a good reason to put install low-efficiency cast iron in new construction since, as you correctly concluded, a chimney of any kind is impractical.

People still use cast iron boilers for the same reason the you will find the kickstand on the left side of a cycle...because your great-grandpa got on every horse from the left.
If you want Weil McLain we like the WM97 and the ECO for real value.

First proper ACCA Manual 'J' performed on dedicated radiant software by an experienced designer.

 

[Cookieman]

Cool, thanks Dana, I'll look into it. The house will be pretty tight, full spray foam walls R21 with an inch in the roof for air seal and R60 up there. All triple pane windows.

 

[Cookieman]

Badger, thanks. The only reason for the supplemental rads is that that room has 20' ceilings and a wall of glazing in front of it. 144 sq. ft of it. I was pretty diligent in getting the numbers for the calc. however I have been known to be wrong.

 

[Cookieman]

So Dana, if I got a Versa, will it still do the rads and the unit heaters?

 

[Dana]

The Versa series have about the same max-temp outputs of most mod-con boilers, and come with outdoor reset control, etc.

http://www.htproducts.com/literature/lp-314.pdf