Radiant heat installation

Unknown

but the second opinion is most likely correct. Radiant should almost always have primary-secondary piping when used with boilers, and some kind of mixing.

You might be able to get off a bit cheaper with a "variable speed injection" system, but it wouldn't be a big savings.

You are lacking (it sounds like) "mixing control" and "boiler protection". You might be able to forgo mixing control by turning the boiler down a bit (though that certainly is not ideal), but boiler protection is pretty important.

Wes_2

Radiant heat installation

Hi all:

I am a homeowner who renovated a 100yr old house last summer. We had a 2 zone radiant heat system installed. Zone 1 (Bathrooms)in subfloor, zone 2 (Kitchen) tacked up under existing hardwood flooring. The Wirsbo PEX tubing under the kit. floor was not installed or insulated properly so we froze our tails off last winter. Found the Wirsbo installation handbook on this site (Thanks!)and now know what our installer did wrong.

But my question to 'the wall' concerns the boiler that feeds the radiant coils... When a new heating contractor came to look at my steam (main) boiler he examined the Crown Aruba and said that it was not done properly.

Evidently, it was installed so that the hot water leaves the boiler, circulates and returns. Simple as that.

Well, heating guy #2 said that the water leaving the boiler is too hot (180 degrees)(could damage floors) and water returning to the boiler may be too cold (damage boiler) and that to be corrected would need such things as 'primary and secondary piping and mixing valves' to regulate the water temp.

Having spent $3,800. to have the system installed last year, imagine my dismay to get an estimate of another $3000 from the new guy to do it right. Obviously, I would like to go back to the original installer and have him do it correctly but now I just have one profissionals opinion versus another.

Can anybody out there weigh in on what is right? What do I need to tell the original installer is lacking?
Sorry for the length of this post.
Thanks so much
Great site!

Joe_51

Did the origional installer do a heat loss calculation ??? There is no way you should have to freeze your butt off if the job was done right. Rob's advice is dead on.

Justin Gavin

Those prices seem high

If you have a boiler feeding 180 degree water under your hardwood floor you are going to have some problems. Did the installer use aluminum plates on the staple up. If not that could help the heat situation out a little bit more.

Your initial cost for $3800 seems too low and the estimate to fix the problem seems to high. This is probably where the problme lies. You get what you pay for and unfortuanately you were on the wrong side of that equation.

Good Luck,

Justin

Ted_9

Justin, I hope you are not say the $3000.00 to repipe a boiler with professional controls using outdoor reset is too high. I'm not starting trouble here, but that is NOT TOO HIGH. I dont care where you live.

Ted Gregoriadis


Patriot Heating & Cooling, Inc.

clammy

i'm with ted

If 3 grand is to much for p/s piping and reset control then thats why i rarely see them as the dudes in the local supply house who distrubits wisbro contuines to say no heat loose needed no reset or variable speed pump just a mixing valve ,circ relay and a stat says everything is not needed i find that hard to believe says all the jobs they do never have a promblem or maybe they just don,t answer the phone new york state only seen about 4 or 5 radiant with auto mixing valves evrybody goes the cheap way i have always tried to sell the correct way p/s and reset thruogh a 3 ways valve but i,m always beat by some guy coming in super cheap and telling the custermenr they don't need all that other stuff ya got to love it clammy peace

Dana

I,m fixing a system now that is almost exactly the same situation for 7500. Whoever installed this sytem had no idea what they were doing with the radiant or the boiler installation. The homeowner paid this guy 6000 to do it wrong and he's no where to be found now. I look at and fix heating systems weekly, both simple and complex.

Pinball

Steam Boiler?

Was I the only one who noticed the homeowner said she had a steam boiler?.While I am not an expert, I do think the temps. would be much higher than 180. unless of corse, the radiant is going through a tankless coil on the boiler. In which case it would seem to need only a three way mixing valve and a lower setting on the low limit aquastat. or am I way off base?... maybe I can learn something here.
Just my two cents worth. which might be all it is worth.
Al

Ted_9

Jeeze I thought she meant a steam boiler was suppling heat to the house though cart iron rads.So your saying that there is a hot water loop off the bottom of the steam boiler? Thats interesting. I forsee the price to fix going more that $3000.00 to do it right.

IMHO.



Patriot Heating & Cooling, Inc.

Pinball

hmmmm? Crown Aruba steam?

After reading it again, you might be right. Does a Crown Aruba come in a steam version? Like I said I might learn something here as well. Like maybe how to read !
Al

Wes_2

Radiant heat installation

Its me the homeowner again - (see my original post)
The Crown Aruba is a hot water boiler that is used exclusively for the radiant heat on the 2 zones described in my original post. The steam boiler heats the rest of the house.

After checking the Wirsbo Installation Handbook again, I found on page 87 that the recommended water temp (for residential applications) is between 95 and 165 degrees.

Upon closer examination of the boiler, I found a Honeywell thermostat that can be set as low as 140. Couldn't my installer argue that any setting below the Wirsbo max of 165 is acceptable and achievable without mixing valves and primary/secondary piping etc. Would he be wrong? How would I counter that argument?

Is this approach what is referred to here as 'downfiring'? If so, why is downfiring bad for boilers?

kevin coppinger_4

Charlotte....

nice thought but the boiler you describe is not designed to run as you descrbe it....the 140F is a minimum and if run at lower temps from the radiant could cause the inside of the "firebox" to condense and damage the boiler....the cold water from the system will shock the boiler and shorten its life too. What you really need to do is find out what the design of the system IS or SHOULD be....otherwise we/you are just guessing...when it gets very cold you might need a supplimental heat source w/ the staple-up design....get a contractor/engineer whose has done many of these systems....good luck , kpc

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hr

If this is a suspended tube

installation you may need 180° degrees to meet the load. 180 supply at 20 degree delta T with a R1 floor covering and 65° room temperature puts out about 22-24 BTU/ square foot.

Better get a load calc done, pay attention to floor covering R value. THEN get your ducks in a row concerning needed supply temperatures for your application.

Without a load calc and desigh everyone is just guessing

hot rod

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Weezbo

Whatever the boiler thats way high for the pex to be seeing.

yah its been done and probably will be done again :)thing is thats heat straight out of the boiler Bang into the floor chillin Bang back to the boiler 3 mins later.something needs to slow that process down...anything...buffer tank...modulating mixer,set point bypass, and that is to protect the Boiler not heat the floor:) isnt that weird:)now this is a guess buh if the pex loops have air in them it is quite likely you spent the entire winter freezin yo tail feathers off. ahmmmm...oh yeah...a spirovent is a handy somnagun for just that sortta deal.....if you temper the water temps dpwn...say to 68¡ãF and just call it good youd probably better off than big fancy numbers in the 100's my slab is on the cruise right now at like 78 cause i am home sick the room temp is 76/77 when i am at work its on cruise in the 60¡ãrange room like 58/59. you are making me feel guilty i'm not working today...:( dr says i got walking pemonia or some such on top of this flu bugg. everybodys making me stay home and get rest i hang around the house thinking about all the houses and boilers i got to get finished...i dont want anyone else to get sick either i have been eating walls for over a fortnight sick aint a good thing to be...... oh before i forget the cost of the installation sounds like they were in and out and gone:) the reason is we have to do a large volume of work in order to stay up with the bills .... maybe you caught them when they already had way too much work to do and the just banged it in to get you heat. the finess part is well worth the dollars...it does require a bit of time though.maybe thats why your bid was as low as it was.

jerry scharf_2

try to sort out a few things

Charlotte,

I really feel for where you are at. It's sad to hear that yet another person got the job done wrong, and are now facing having to do it a second time correctly. You sound like you are already on the path to learning enough to get the system you need. Your questions are excellent.

Like HotRod said, the starting point is to do a heat loss calculation for the areas being heated. Since it's only two areas, it shouldn't be too hard. You can go to the pipe on the left and click the free heat loss calcs. The great people at SlantFin are giving away software that will let you do this for yourself. This gets around the who says what of how much heat you need. With the loads and the surface area, you get how much heat you need to get out of the floor to heat the system on the "design day" (coldest of the year.)

Second, there are a couple temperatures that may seem confusing at first. One is the maximum heat that the floor sees, the other is the minumum temperature that the boiler sees on the water returning from the radiant tubes.

The general guideline is that you don't want the surface temperature of the floor to be above 85 degrees. This is a safe and comfortable number. You will need water hotter than this to get the heat from the pipes to the top of the floor. The temperature of water needed depends on the type of installation and the details of the installation. I think just about everyone on this site prefer the use of high quality heat transfer systems. Can you take a few pictures of the actual piping under the floor and post them here? It will help us to help you. With this and the load from above, it should be clearer how hot the water you need is. A word of caution, there have been a number of systems that have come here where there is no possible way the tubing installed can ever keep up with the load.

Second, there is the return water temperature. The boiler you have is not protected from low return water temperature. If you allow cold water to flow into the boiler, it will cause moisture to condense inside the boiler and vent (exhaust) pipes. This condensate tends to be acidid and will eat up the insides of the boilers and vents in a few shrt years. So there needs to be some form of mixing of the return water from the radiant and hot water out of the boiler to keep the water returning to the boiler above 140 degrees. Again, pictures of the boiler and near boiler piping will be a big help.

Finally, since you are almost certainly looking at some repiping, you might also want to look at a control system that provides "outdoor reset." This is a system where the water supplied to the radiant pipes varies with the outside temperature. As the outside gets colder, the water gets hotter to keep up with the heat demand. It can save some money, and increase your comfort. Since you will need some control to protect the boiler, this may be a good additional investment. Make sure the installer knows the products they are installing.

wishing you the best, jerry