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Joined on January 19, 2012

Last Post on July 28, 2014

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@ August 16, 2013 12:01 PM in Slab overpour "Radiant Green" hydronic heating panels?

First off, radiant green and dent both represent the manufacture.
If the manufacture is going to make claims it should be backed up with actual test data. The average insulation value is of no use. The actual r-value under the tubing is all that counts. The myth of reflective coating under concrete has been totally debunked. It is absolute voodoo. Placing the tubing at the bottom of a thick slab is also a bad plan.
I am not saying that this is a bad product. It is very difficult to tell without the facts. I do know that my building department would not allow me to use it due to lack of actual test data. We are not trying to prevent scalding from coffee. We are trying to design an efficient and comfortable heat system. This product does provide some insulation, just like a coffee cup. The question is, how much?


@ August 16, 2013 11:32 AM in Pex spacing for under floor radiant (joist bay)

You just have to do the math.
Until you do a heat loss calc you are just guessing. What you have would work in a super insulated home. There is only one way to know if it will work in your home.


@ August 16, 2013 9:38 AM in Pex spacing for under floor radiant (joist bay)

The fact that you have plates is a huge plus.
I think, rather than starting a war based on "rules of thumb", you should have the proper calcs done, then decide if the system is incorrect.
I think it is very likely that your problem could be resolved by redoing one or two loops only in the high loss areas.
I would suggest finding a reputable designer, having the calcs done, then requiring the contractor to make the necessary modifications.
Would it be fair to offer to split the cost of the design with the contractor? You could strike a deal where whoever is right pays the bill. In some areas this service is provided at no charge by the supply house.
In the end, you just want the comfortable efficient system you were promised. Proper design is the only way to get there.


@ August 15, 2013 2:31 PM in Pex spacing for under floor radiant (joist bay)

There is no simple answer.
The correct way to design a system is:
1 Do a heat loss calculation on the home.
2 Determine how many square feet of flooring is available to emit heat.
3 Size you radiant panel (tubing layout and aluminum plates) to meet your specific heat loss.
I am guessing your contractor did not do (and does not understand) any of this.
If you have 16" OC tubing with no plates, you are not going to heat anything.

You might try the RPA for more info



@ August 14, 2013 6:24 PM in Radiant Heat not Heating

How about posting some pictures of the piping.
It sounds like your delta t is high between supply and return.
You may also have low flow. If the zone has a mixer, what model.What size circulator?


@ August 14, 2013 9:23 AM in Radiant Heat not Heating

If the exchanger is bad, you would not be getting enough heat or flow. Since the slabs work fine and the staple up is too hot to touch., it seems unlikely. How hot is the return on the staple up?


@ August 14, 2013 1:53 AM in Creatherm panels

I assume you work for the manufacture?
I wasn't originally questioning the r-value. Now that you mention it, I don't see an EIS report on the web site and I see words like "average r-value". It is less under the tubing, yes? Is the report available? It also seems that the tubing is not fully encased in concrete. It is touching the foam on the bottom and most of the way around at the turns.
See the attached article from an industry great.
The depth does matter.


@ August 14, 2013 12:14 AM in Creatherm panels

The goal is to get the tubing centered in the slab.
This product has the same problem. The tubes are at the bottom of the slab.


@ August 13, 2013 10:12 PM in Converting from oil to natural gas - Navien CH210 was recommended

You math is perfect.
Of course you need a heat loss.
It's funny, when no one comments on my posts, I figure I got it right and there is nothing else to say.
Sometimes, I think I said something so wrong, no one wants to comment.No, no one would let that go.
I would take it as a compliment.

I'll take the picture on the right.

@ August 13, 2013 7:33 PM in Primary / Secondary Basics

I'm not sure what you mean by "slinky" and "ferris wheel".
You have it piped backwards.

Condensing boiler

@ August 13, 2013 6:42 PM in Proper Operating Temperature for Weil-Mclain boiler

The way you have your system set, you are causing condensation in a non-condensing boiler. The condensate is acidic and will eat the boiler and flue pipe.
You are correct that you should run as low a temp as possible in your tubing. Running lower temps will also  lead to greater comfort as the system will only heat the floor as needed and will overshoot your indoor temp less often.
I would suggest a mixing setup with outdoor reset.
If you elect to not upgrade, set your boiler so that your return water temps are greater than 140.


@ August 13, 2013 8:19 AM in pump control wood heat

Just get an aquastat with both N/O and N/C terminals. It will close the circuit under the conditions you desire. 


@ August 12, 2013 11:39 PM in Radiant Heat not Heating

Without a drawing or a wider view it is hard to tell what is going on in your boiler room. I agree with J star that there are some things that look suspect.
One 3/4" tube every 16 inch does not make for much of an emitter. Is it stapled or hanging? Does it have plates or fins on it? I would guess that a bare tube assembly like that would have trouble making more than 10 btu/ft. I imagine your house loses more than that.
Have someone do a heat loss calculation and add the appropriate emitters. Panel radiators come to mind.

My Point

@ August 9, 2013 7:01 PM in Converting from oil to natural gas - Navien CH210 was recommended

I absolutely agree that we shouldn't size boilers by available radiation or existing size. I was trying to let the OP see for himself that his present boiler is clearly over sized.

There are a ton of different condensing boilers out there. Lumping them all together is is like saying you are not going to buy a Toyota because Yugo makes a bad car.

Buy a good condensing boiler and enjoy the comfort and efficiency they provide.



@ August 9, 2013 5:07 PM in Converting from oil to natural gas - Navien CH210 was recommended

Blindly replacing a boiler with the same size is not a good practice.
I wouldn't expect every contractor to a thorough heat loss on the first visit. It should be done before the project begins. I would expect them to determine the size of the house, lineal footage of baseboard and ask some questions about your hot water needs.

If you are curious, measure all you heaters and multiply your total footage by 600. This will give you the maximum amount of BTU's your house could possibly need.

The Navien is a lesser product than other condensing boilers. It comes at a lesser price.
Your call.



@ August 9, 2013 8:52 AM in DHW mixing valve and check valve requirements?

Some manufactures put integral check valves in the mixer. No need for another in that case.
Is long as the owner is OK with a little hot in the cold and cold in the hot, don't worry about it. I have found people have this crazy notion that when you turn the hot handle you get hot water and when you turn the cold handle you get cold. The other thing they like is once you set the temp to the shower it stays at that temp. They just don't like it if gets scalding hot when the washing machine downstairs turns on.
Seriously, if you don't have check valves, slight pressure differences in your system will cause cross flows that will annoy the owner and then, in turn, you.


@ August 8, 2013 11:58 PM in pipe ID and flow/BTUs

You have a reasonable amount of mass. Not great but workable. You can always use add some storage tanks later. You are not going to hurt the superstore with high temps.
How are you going to control it? The backup will heat the wood boiler when the wood fire goes out unless you do something.If you use wood 99% of the time it is not a big deal. I wouldn't elect to put the backup boiler in series as you have it as it just gives up heat and makes control more difficult.


@ August 8, 2013 9:35 PM in rarely

Paul,You have a condensing boiler with a very high efficiency rating. You only get that efficiency if you are returning cold water.  Check this out

The boiler will only fire to the temp calculated by the outdoor reset.
The warmer the day is the lower the temp you will have to run, the more efficient the boiler. No mixing involved.
As for the temp, it really depends on the design. I realize you don't have all the info.
Your high will likely be around 120.


@ August 8, 2013 6:51 PM in rarely

Maybe I am looking at the wrong install manual. Does your boiler have an outdoor sensor and reset capabilities? If so you don't need a mixing valve. It does not look like you need flow checks. Make sure you give yourself a way to purge the radiant loops and the boiler.

Great subject

@ August 8, 2013 4:20 PM in kill overheat with wood furnace

Hot Rod,
I have seen that too.
It was probably a good thing as the outdoor boiler had no glycol.
As for the OP, I think he was a "One Post Wonder"


@ August 8, 2013 2:22 PM in DHW mixing valve and check valve requirements?

The only check you have to install now are to protect against hot-cold, cold-hot cross connect. Some mixing valves have them built in.
The other check valves are an entirely different subject.


@ August 8, 2013 2:04 PM in Prevailing wage questions

Interesting stuff Charlie.
Reading through the list it really is just gauge of who has the stronger union. Tilesetter and masons are making 75% more than electricians?
No offense but this comes from the land of politically appointed toll collector making over 100K and A required policeman at every construction project near a roadway. Keep in mind he will never leave his car or attempt to direct traffic, he is just there to right you a ticket after you run over the workers.
Funny Stuff!
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