Mounting a New Boiler

[MarkeyHall]

So after doing a lot of research and finding a lot of great data on this site, I decided to go ahead with the contractor who quoted me $10k for a Triangle Tube (Trimax Solo) 110 with a 40 gallon TT indirect water heater (and all the pipes/pumps/everything in there). The only remaining question that I have is on how to mount the boiler to the wall.

The contractor is planning to mount the boiler right to the foundation wall, not use any type of plywood or anything behind it - does that make sense to anyone? I've only seen examples of where the boilers are mounted to some type of board, never to the bare wall.

Any thoughts?

Thanks

[mage182]

I have a Burnham Alpine boiler. With that unit all the weight is held by the top bracket and the bottom one just holds it to the wall. I drilled two holes through my foundation to the outside, got two threaded SS rods and bolted the bracket to the wall. I used a piece of kindorf on the outside as a brace to spread the load. On the bottom I used two compression anchors that I got from Grainger.

It could be beneficial to just build a dummy wood wall if you have a lot of piping and pumps to mount, I used kindorf on the wall and mounted all my close boiler piping to that. However, the idea did cross my mind to build a wall about 3 feet from the foundation wall so that I could run piping behind it so everything looked neater in front.

[jadnashua]

There are lots of viable concrete anchors that can be used to anchor the boiler directly to the wall. It might only be a problem if you had moisture intrusion and then, even a piece of plywood might be problematic. I'd want to use either a lead anchor or some screwed in anchor, and not a concrete nail (hammered in or shot in), but that's me. He could also anchor some stringers to the wall and then anchor the boiler to those and that would provide a little standoff in case the wall got damp.

[Dana]

Unless this is a leaky older 5000'+ house with no foundation insulation it's unlikely that your heat load is big enough to warrant as big as the -110 in a MA climate. If it's broken up into several zones you may shorten the life of the -110 by short-cycling on zone calls, since the min-fire output is ~28-29KBTU/hr (which is more than 3/4 the measured whole-house heat load at my house at 0F. My house isn't new, and not close to code-min on insulation or windows, but I've tightened it up a bit since moving in.)

You might get the same comfort, better efficiency, and longer boiler live out of the -60, which modulates down to ~15KBTU/hr, which is less my average mid-winter load (and maybe yours), which would yield far fewer flue-purge & ignition cycles, and long, modulating burns for much less stress on the equipment.

If your calculated heat load at the 99% outside design temperature is even as high as 57KBTU/hr you'd be better off with the -60, and it would make very little difference to the overall system design, and might knock a few hundred off the quote. Even if the quote stays the same, I'd still go with the smaller boiler as long as it met the whole house load at the 99% condition.

How was the heat load/boiler-sizing determined? Did anybody do a formal room by room heat loss calculation? Do you have a fuel-use history on this place using other equipment? (An upper bound on the heat load is readily calculated by fuel use and name-plate efficiency of the prior equipment.)

Mounting the boiler directly to a poured concrete wall isn't much of an issue- it works fine.

But an uninsulated foundation wall is worth doing something about in a MA climate too. At the very least consider buying a single sheet of rigid 3" iso (~R18), and mount it to the wall behind the boiler with 3/4" OSB or ply through-screwed to the foundation with 4.5" or 5" TapCons 16" o.c. and mount the boiler to the OSB/ply, then finish insulating the rest of the foundation later. In most 1-2 story MA houses an unsealed uninsulated foundation accounts for 15-20% of the total heat load (and fuel use), whether there's joist insulation between the first floor and basement or not.

[BadgerBoilerMN]

On the heat load Dana is right. On the insulation, I would look the the surface and differential temperature, noting that all modcons have heat exchangers buried in a cabinet and nearly all have air space between cabinet the wall they are fastened to.

I like to worry about the big stuff. My guess is that more than half of the Solo110 Triangle Tube boilers should have been 60. It is certainly true here in Minneapolis. All for the lack of a simple heat load analysis.

[mage182]

I concur. Buy the correct sized boiler for your need. It took me a long time to tweak my boiler to work the way I almost want it to since my installer sold me one that is way oversized.