underfloor wirsbo design

ScottMH

I had a plumber design and install a 5/8" wirsbo system under floors in our 180 year-old renovated farmhouse. The 3-zone system is fired by an 80,000btu 95% efficient natural gas boiler. The system is not keeping up with the heat loss, even with the mild fall temperatures near Erie, PA. The tubes were put on 18" - 26" centers in aluminum heat transfer plates between the old logs that support the floors. I fear the tubes are too far apart, and the system was underdesigned. How do I find out for sure, and what can I do?

Al Letellier

radiant design

I would find out who the plumber used to calculate the load and design the system, and get copies of the computer print out. Does sound like the spacing is off. Old floors do create challenges. If all else fails, contact the local rep of the materials used. The brand name is usually stamped on the tubing and they all have web sites.
A consultant will cost you money, but may be the best alternative.

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Cliff Brady

Does the system have outdoor reset control?

Maybe the boiler's set point is being throttled down by the outdoor reset curve which may be easily adjustable. Is there a thermoter to see what the supply temperature is? Are the floors feeling very warm when it is cold out?

kevin coppinger_4

what is the ...

design temp.? What do you have for insulation? How is the temp. controlled? (mix valve, injection, etc.)I n a staple up application 18"-26" centers sounds way too wide...should be more like 8". Where is the contractor? I would hope he would come back... who did the design? good luck kpc

Tom Bradd

What temp is your supply water ? do you have a condensing boiler ? what type of plates that would lend you to a spacing of that size ? How much insulation do you have under the plates between the joist. and what type of floor construction do you have on the floors plank what is your upward r-value ?

ScottMH

Here's some details, and more questions.

It's a MUCHKIN boiler model 80M. The outlet temp reads 150f right now. When the system was trying to keep up last weekend, the tubes were so hot you couldn't hold on to them, yet the room above was 62, and the thermostat was asking for 68. A Taco 4-zone relay controls things, Taco mixing valves are used, and there is nothing reading the outside temp (should there be?). The heat transfer plates are extruded aluminum wirsbo brand 1/16" thick and 4" wide by 48" long. I have put 1/2" foil face celotex under the tubes. The floors vary in thickness, the bedroom has a thin plush over special padding especially for heated floors, 1/4" underlayment, and 1" planking. The kitchen has new ceramic tile over 1/4" cement backerboard, over 1" planks. The installer/designer suggests more insulation under the tubes, before I do that, should I put up more tubing? How is the center to center distance determined when designing a system?

Tom Bradd

Rule of thumb is a 5 to 1 ratio below the floor as above.The tube spacing is based on the heatloss of the floor. I think you need an outdoor sensor probe if the boiler/controls have outdoor reset.I would as the installer to provied you with your load calculations. Send them to Wirsbo and have them check them,even if there is a fee you better find out now. Is the system still under any type of warranty? What does your installer tell you? but insluation is a HUGE issue to overcome the floor above. 1/2" insulation is 2.5 I think. Question.. what is the temp like below the tubing in that room or area ? is the Heat going down ?
good luck

Steve Eayrs

A simple answer to the spacing of tubing you need under your floor is based on the btu's per square foot needed to heat your place.

I would venture to guess that no heat loss was ever done, and no manuals or general specifications were looked in determining what you needed, but simply what was would be easy to install. If this is an old log house, in a northern climate, I would guess that even with the tubing on 8" centers, there could still be rooms, (based on someone doing a heat loss), that would require additional heat to meet the load. (like baseboards, or other)

You may want to get a heat loss done, by someone else, before doing anything else. Not many places that 18" tubing centers will work on, even in a concrete slab.

Steve

Floyd_5

Sounds like you are way short..

on tubing and plates. If the boiler can get the tubing that hot you have enough poop in the boiler just not near enough transfer surface. You need to probably at least double the amount of tubing and plates that you have there. With that boiler you don not want to be running such hot temps. in your tubing. That boiler will run much more eff. and still heat fine if you can get you tubing temps way down (100-120)and still get enough heat. Insulating underneath to a higher R value will help, but that will not give you near what you need. With what you have there you definetly want to add a couple inches mmore of foam under neath but first do yourself a favor and rip down what you have and install tubing so that you have a min. of 12 in centers, taking into account that you are losing the area the those big beams take up, so that may mean that you cram two or three rows of plates and tubing in between the logs with very little space between them. By the way... what did you do at the ends? did you drill through those big logs to get the tubing through or did you drop the tubing down under the logs?
Did you have a heat loss done? That little 80M will heat a bunch, but it has to be able to get rid of the heat it produces so well.

Floyd

ScottMH

A great deal of thanks, and some questions answered

Thanks to you who have replied here, as well as those who contacted me directly. It's reassuring to find honest, caring people willing to share opinions and experiences without looking for something in return.
It seems from most of you feel I need a good bit more tubing. I'm very tempted, however, to just put up a mess of insulation under the tubes. Is it everyone's opinion that tubes like this, even with 4" extruded transfer plates, placed 24" on-center, won't do the job, even if the water temp is high?

When I get the tube spacing correct, I still have a zone upstairs where I can't get to the tubing, now that my ceilings are all finished. Has anyone tried to regulate a system where one zone has not enough tubing? Is this difficult?
Answers to questions:
The installers did not drill thru any beams, even the newer ones that were actually saw-cut lumber, all the tubes "loop down". How important is that? The installers also did not have the extruded aluminum heat transfer plates touching end-to-end, they put one a couple feet from the wall, then the 4' pan, then 2-3' of tube with no plate, then another pan. Is this a common practice? Whether I have the original contractor back, or hire $omeone el$e, I would like to know what it should look like when it's done right.

Mark Hunt

18 to 26


centers eh?

Hire someone else.

Mark H

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hr

It's not too late

to do a heat loss and design. Not much sense in going further without one! The floor covering R value also plays a BIG part in the equasion. It will all become clear with some number crunching

hot rod

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Radiant Wizard

Find someone

to due a "Radiant" heat loss and design. Sounds like your installer doesn't now how to install radiant. Your floors have a very high R-value you need more plates and tubing.

ScottMH

Searching for the right contractor

I've attached a picture of a typical joist space in the oldest, original portion of our home. The rebuilt portions of the home, where joists are on 16" centers, also have just a single tube down the middle.

It appears all agree I need more tubes and plates. A gentleman from wirsbo contacted me and, I hope, will soon steer me to finding someone to help me fix what's been done. My original contractor has not responded favorably.

I wanted to ask out here on the Wall, does anyone know who may be able to help with an assesment and redesign and reinstall? I'm an hour east of Erie, PA. I'm looking to find someone who is experienced in doing things the "right way" according to Wirsbo.

Earthfire

design

This install is a bad _________ installer design. The tubing manufacturer is not at fault for a bad install. If you are going to name a system use the name of the installer not the component manufacturer.I believe in naming names and giving credit where credit is due. DON'T DO THE CRIME IF YOU CAN'T DO THE TIME. JMHO

ScottMH

Exactly.

You are correct. I hope no one misunderstands where my trouble came from. Wirsbo has been 100% helpful. I didn't even have to go to them for help, a technical services manager contacted me when he heard of my troubles. I chose Wirsbo becase of my good experiences with them years ago, I've just had bad luck this time with an installer and now need some help.