Looking for the facts........

mikea23

Fact radiant systems are more comfortable but just like forced air propery designed systems only. In my experiance 30 to 40% more is a reach at best. When I sell Radiant I dont talk about energy savings only comfort. True energy savings is hard to calculate. I would say if the system is designed properly in new construction maybe 10%. You can do all the numbers and it will show a substantial diferance on paper but to get real numbers you need infultration rates (blower door test).If the customer is looking for true savings The building envelope is key. his system is just a bonus

Simply Rad_2

Looking for the facts.....

We all know that radiant heating is more comfortable than forced air. We also know that radiant heating is more energy efficient than forced air too. I have read 30-40%, but are there any true examples for facts to prove this. My customers is interested in the difference.

Jeffrey

Jed_2

Actually

I have been shown and experienced the results of a properly designed forced air system that is every bit as comfortable as a radiant system. Add good filter system, and you have consistantly fresh, even comfort. I'm specifically referencing 2 SpacePak H/C systems. Walk ANYWHERE in the conditioned spaces, and I defy you to measure more than a +/- 1°F variance. It can be done, has been done. In these cases, PurePak air filters were deployed. Yes, there may be life cycle costs of the blowers plus circs in these hydro air sysems. But the comfort levels achieved are outstanding. Add in high efficiency boilers, variable speed blowers (the systems I reference do not have variable speed blowers), and I suspect the operating cost would go down further.

Rad, I wonder where you are getting the 30-40% numbers. Sure, most, if not all, standard large duct forced air heating systems are most likely poorly designed and sized. Hence, poor efficiency and performance. I'm saying it doesn't have to be that way.

Jed

Chris_82

I don't really know how accurate some of these numbers are....

But I know that I waited 30 years in this trade to finally heat my floors, and have great regrets that I didn't do it sooner!

One of the big concerns for me was that the upohnor /Wirsbro people continually sell comfort over cost...Well we installed warm floors with cost as a real concern...it can be done, it should be done, but it is difficult to do! The devil is in the details as they say. Neverless if it does cost more to install, it is worth it!

Jed_2

Envelope

Mike, I couldn't agree more. The envelope is critical. One the installations I mentioned was heavily Corebonded throughout. Nada infiltration. The Builders must get on board, or it's all for naught.

Jed

Simply Rad_2

Sorry

I did not mean to say or intend to start a discussion on the comfort of radiant heating and forced air. I was just looking for the operation cost comparision between the two.

Jeffrey

mikea23

Thats a hard thing to do in the 20 years doing this I think I have looked at maybe 3 properly sized and designed residential HVAC systems. For the contractors to follow standards the cost are to high. so how can you compare that

Brad White

I think the real comparison

is going to be empirical, experiential if not anecdotal. Unless the RPA, Brookhaven National Labs, Berkeley-Livermore or other organizations have done published studies, it may be just individual experience.

In the end though, I think the operating cost edge would go to the system using the coolest water temperatures generated by the most efficient means. To me, 100 degree water trumps 130 degree or hotter water every time.

DanHolohan

Historical

This is in the Library Comparative Cost of Radiant Heating See pages 8 & 9.

There's more like that sprinkled through those old articles. As far as I know, no one has done side-by-side comparisons since.

It pays to wander off the Wall.

Unknown

Not side by side comparisons

but when we convert those ol' Levitt homes from radiant floor heat to baseboard , there is an increase in fuel usage .

I had to convert mine to BB 8 or 9 years ago . I didn't track fuel usage . But I know we'd all freeze our hineys off if we kept the thermostat set where it was with the radiant .

The house wasn't insulated at all when the radiant worked , and not a cold air draft could be found . Now , with 2 of the 4 walls insulated and all new doors and windows , we got plenty of draft still . And a huge humidity problem . I know - tighten up the envelope more . But these weren't propblems when the radiant was on .

[Deleted User]

Funny thing...

A few years back, the RPA asked all of its members to contribute to a data bank of information, attempting to ascertain the very same thing. Few, if any people actually responded. Not sure if they were just too busy, or if no one had any data. Personally, when I converted my home from GFA to hydronic, I reduced my energy consumption by over 50%, but that is just MY home.

As for our customers, when we convert them from FA to hydronic heat, they typically see a slight increase in fuel consumption but a HUGE increase in wall to wall comfort that more than offsets the minor fuel consumption increases.

I do have one Habitat Home that NREL monitored for over a year on a minute by minute basis, but it has solar PV and solar DHW on it so it too would not be a fair comparison to the neighboring houses.

As Brad mentioned, annectdotal at best...

And then there was the whacked out Canadian Home Mortgage study...

ME

hr

A slippery slope

when you start suggesting energy consumption figures.

I can say with confidence that hydronics can move the load with a much lower electrical consumption

Comfort could be debateable also. FA can heat cool, filter, humidify, dehumidify and exchange air.

But FA is hard pressed to warm floors walls and ceilings The IDEAL system would be a blend of both.

hot rod

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