Help with specifications

Al Letellier_9

Gene, I do this for a living as part of my consulting business, so I can't be too specific, but I can say that if you want apples/apples pricing you need to get very detailed with your specifications. I would required all bidders to bid on your specifications, then chose your contractor and then negotiate the "or equals". That phrase alone will change apples/apples to oranges and bananas.
I would also recommend that the bath always be on a separate zone. If the stat is in a bedroom and gets tunred down or satisfied, the bath will be cold. Especially if it's ceramic tile on the floor. Use a stat with floor sensor for year round comfort in the bath.
Specify the boiler you want and the type of radiant tube, specialties and piping and manifolds to get correct, on the same page pricing. Its the only way you can't get confusing pricing.

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Gene Davis_2

I need help with specifications so that a request for quotation to multiple heating contractors can generate proposals that can be compared "apples to apples."

If I don't do this, I get proposals for systems that vary widely in performance and price.

Here is what I want to say so far: Heat system to be LP-fired radiant hydronic, boiler to be 87% AFUE minimum, basement to be heated with tubing in slab on 24" centers, mainfloor to be done with above floor installation, Wirsbo QuikTrac or equal, two zones, bedroom/bath end as one zone, greatroom end as second. Greatroom will require (4) wall radiator units as supplemental heating, 6000 Btu/hr minimum each, approximately 24" h x 60" w, each under a window.

Upper floor to be done with under-floor system, using extruded aluminum plates. One zone for bedroom, closet, bath.

What more should I say? What about controls? Thermostats? Outside sensors? What should be said, if anything, about the radiators, so that all are bidding on an equal basis?

The RFQ package will included drawings, window and door schedules, glass specifications, insulation specifications, building site conditions and orientation of building, and room size info with ceiling heights and types.

S Ebels

Change your specs

I would think you'd be asking for a true condensing boiler given that it appears your system is mostly low temp. 87% is borderline condensing and you could wind up with a radiant wannabe boiler. IMHO, 24"is to wide for practically any application except a footbal field sized warehouse. Granted, your basement may not need closer spacing for the raw output but spacing of 12" will do away with most of the "striping". You'll also have the advantage of being able to run lower water temps in the floor and increase your system efficiency.
You could also do the upper floor in panel rads instead of staple up and eliminate needing 4 water temps which you're probably at right now. That would be your call of course.

Outdoor reset of each zone, with possible exception of the basement, along with a room sensing indoor feedback device of some kind would be mandatory in my book.

As far as specifics go, take the boiler for instance. Say you requested a boiler that runs at 90%+ AFUE. Using that as the only criteria, you could get quotes on anything from the most humble excuse for a boiler out there to a Vitodens. You'd see a large difference in the price quote and from appearances they would seem to be bidding apples/apples. Nothing could be further from the truth.

Maybe it would be beneficial to invite several contractor over to discuss design before you ask for any pricing. Ask them some questions and let them ramble. You'll soon be able to tell the wheat from the tares.

Above all, don't get hung up on the details of the project befroe selecting the right contractor. Getting the right guy is paramount to getting a nice running low maintenance system that will last a lifetime.

Gene Davis_2

Thanks for the suggestions. How does this sound. Boiler to be Weil McLain "Ultra." Radiators to be Myson "Select" series. Do basement as one zone, tubing in slab spaced 16". Mainfloor three zones: greatroom, bath, bedrooms & hall. Heat upper floor this way: above-floor in bath, with small radiator supplement under window, all in one zone, then master bedroom as second upstairs zone, heated with radiator only (no floor). Outdoor reset all zones except basement.

Brad White_87

I would go further than that

What Steve and Al said certainly applies. Without a full design (layout of tubing etc.) you would want language in there to the effect that the space shall maintain say 72 degrees F. at an outdoor design of 0 degrees F. (or whatever is local to you)... using a water temperature not to exceed (120 degrees? 100? start somewhere)... Tubing spacing/density shall produce a floor with a temperature not exceeding (84 degrees?) maximum... make it performance-based in the end.

Will you dictate that the bidders perform heat loss calculations? And to what standard? Manual J? ASHRAE? Generally this will not be expected for a quote but the successful bidder will need to do this and provide documentation.

If as you say plans will be provided, you might use the plans to define zones, what rooms will share a common thermostat.

Short of actually dictating the heat loss of each room and giving it to them, you will wind up with a range of proposals... but the exercise may be a place to find the contractor most willing to work with you...

My $0.02

Brad