How do you guys put out an RFQ for heating, so that you get bids back for comparable systems?
I’ve got new construction, no A/C required ever, want to heat with hot water, PEX tubing in the slab in the unfinished basement, and Myson “Select” series panel radiators everywhere else, using 140 degrees F input water.
The spec for 140 to the radiators comes from advice at THE WALL heating help web forum. Apparently a high efficiency condensing boiler doing a mix of in-slab hydronic and radiators will perform quite well doing the radiators this way.
I can describe all my zones with the plans, and window and doors are all scheduled and specified, as is the insulation scheme.
We have specified a Weil McLain “Ultra” wall-hung condensing boiler, fired with LP gas, and will accept a Buderus GB142 as an equal. Thermostats are all to be Wirsbo, number A3030012, “heat only.”
What we don’t have, is the software to calculate the room by room needs for BTU/hr input, so we cannot spec out the sizing or number of panel radiators, nor the size of the boiler.
And, other than knowing that an outdoor thermometer is needed, t-stats for the various zones, and mixdown gear to pull down the input temp for the water to the PEX in the slab, we don’t know enough about controls to get specific.
BTW, the various bidders are well know to us, and all do high quality work.
Edited 6/30/2006 5:00 pm ET by Gene_Davis
Edited 6/30/2006 5:07 pm ET by Gene_Davis
Replies
If you have a few possible subs who all do high quality work, I would not write a detailed RFQ. I would simply outline the basics (# of zones, boiler spec, t-stat spec, rads, etc.) and indicate that they are to do the heat loss, design the system, install it, test run it, and provide whatever followup service you want. The different bidders will have different approaches and will pick up on various things about the job that you had not thought of. By reading the proposals you will see who's the most on-the-ball and who's gonna cover yer butt the best. If you write an RFQ that is highly detailed, the bidders will be constrained by that and it may limit the quality of what they propose (based on your limited knowledge of their trade).
I would make sure that each bidder clearly specifies who is responsible for other parts of the system that they don't do, i.e. gas lines, venting for the boiler, electrical connections, insulation etc.