Does anyone have any experience with Warm Board Radiant floor sub flooring? Is it worth the high cost? Thanks for any input.

we do lots of warmboard jobs. it can be worth it if:

1. very high performance is a benefit.. high loads, and/or heat pumps especially
2. if you have somewhat high labor costs, it can reduce that cost significantly which makes it more attractive.

There are times it doesn't fit... cheap labor, low output requirements, stuff like that. and all overfloor methods have to watch out for punctures moreso than underfloor.

we are heating and cooling our shop with our warmboard... 85 maximum water temp requirement in the winter. We are a very well insulated situation, but you can't get that kind of performance out of most other panels, that's for sure.

Thanks for the reply. Have you ever used any of the other surface board radiant systems that are not structural? I think radiant complete was one. Still trying to get a price to see if it is more cost effective with similar results.

I've used pretty much everything, and warmboard does have a retrofit panel now that is not structural.

If your heat load is very low, panel choice will matter less typically. In fact going overfloor itself can be called into question in some cases. I've got some suspended tube systems running 110 degree max temps out there... but that's a particular circumstance, for sure.

Most other panels will require significantly higher water temps to achieve the same output. Exceptions include Roth, Raupanel, thermofin U tight on center installations.

Rob:

A correction and an addition:

1) WB's new panel is actually structurally rated. Don't yet know what the span rating is, but their patent requires a structural rating or they trip on either Quik Trak or Ecowarm/Themalboard's patents.

2) Exceptions should also include Ecowarm (West coast) and Radiant Complete Panel (East coast - same product, different branding). Water temps are only a couple of degrees higher than WB. Still uses 1/2" PEX.

Barry E. LaDuke
LaDuke Radiant Sales (dot com)

I would call their rating more than "couple" of degrees higher. But then, it's not like anyone actually tests these panels with scientific rigor. I kinda wish we could force them all to...

The bottom line is dollar for dollar what would you use. To do a house in new construction would cost me around 13K for Warm board. Radiant complete panel would be about 10k but you have to add another 2k for the subfloor. I'm sure I can do an under floor system with plates for a lot less but it is not as efficient. Keeping the temps lower is a good thing as far as wb is concerned especially if I go with a geo heat pump. 13k for 1800 sq ft is a bit much and how much extra will the framers charge for the extra work? Thanks for all your input.

we used warmboard. however your answer depends on your heat load to some degree. I've even, in fairly extreme cases, done suspended tube joist radiant with geo and achieved max water temps under 110. but warmboard can do that and still put out about 30 BTUs/sq ft.

What is a typical efficiency difference between Warmboard and some less expensive over floor plates? My guess is that the difference depends on % coverage of the wood and the aluminum thickness. Ie, make those similar and get similar results.

On another note, are there ever any issues with WB and hot spots? Being that the tubing is so close to the surface do you ever feel hotspots when the system calls for heat? This is taking into consideration a wood or tile flooring cover.

Operating efficiency is all about floor covering, effects operating temperature, which in turn can effect the efficiency of the heat source eg. condensing boiler or GSHP.

I have found the difference in output of the various sandwich radiant floor systems to be minimul given the same floor covering. We design of surface temperature after all.

you can easily see a 10 to 20 degree water temperature difference from a high performance to a lower performing panel under equivalent load, depending on floor coverings and what the load is. how big a deal that is depends on the heat source, but I tend to rate it higher with heat pumps than with boilers... 10 degree drop is almost a COP on most heat pump equipment I've seen. Of course reset control reduces this and makes the analysis much more complicated. and raupanel is a high performance panel, it might even beat warmboard in performance somewhat, though at that point we're splitting hairs.

I can say that our warmboard system has very little variance between pipes with a wood floor. it's *very* even. completely unnoticeable to bare feet.

Some additional data here: http://www.fuelcells.bham.ac.uk/documents/review_of_domestic_heat_pump_cop.pdf

COP falls by 0.67-1.07 for every 10°C temperature rise

A typical value (depends on lots of things) - COP=3 for ASHP and 4 for GSHP. It makes for an interesting question of what provides better value - a plastic loop in the yard with air distribution inside or a plastic loop in the floor and air source outside.

Based on UK pricing, I'll guess that the Mitsubishi Ecodan 8.5kw is around US$6000.

that's really useful, thanks. Interesting to see how many options those euros have!!! and note the temperature/cop relationship accelerates as you get lower in the dT... around 110 operating temps (f) 10 deg F (about 6 deg C) can drop almost the full COP for a lot of those comparisons. but it narrows up at higher temperatures quickly.

I do think the variables involved with GSHP are huge compared to ASHP... air is air. dirt is decidedly not dirt however, two sites side by side could have totally different characteristics in the ground. also, with GSHP you have to consider the balance between heating/cooling energy on long term performance... dirt can have its energy depleted faster than it can recover in some deep well situations where the load is out of whack.

I consider GSHP theoretically superior, but potentially much more expensive and in most cases more of a gamble. That said, in capable hands, with good numbers on your side, I do like Geo just fine. with ASHP the only concern is whether the sizing and water temperature requirements of the system are in spec...

Some old studies concluded that hydronic heating didn't save energy. But with the large radiator effect (low temps) on HP efficiency and the reduced air pressure differentials and infiltration caused by ducts, I think it does. The ease of thermal storage is another plus.

Thanks for all the information. Does anyone know of any online distributors of Raupanel? It may another option for me to explore. Maybe more labor for me but it could mean a large savings if I do the work myself.

it's generally even more expensive.

just one way you have you should change your radiant, because if you don't change this you will feel lose.