Another Staple up Question

Chris Maderia

with a question. Is there a mxing valve installed? If not, that most likely is your culprit for the reason the heater is running all the time. Your not utilizing any return water out to your loop mixed with little hot water from the heater. Instead the heater is providing all the water to heat the floors and is continually trying to recover. Start by adding a mixing valve. Other than that only thing that you can do without ripping out anything is raise water temp. There is no other solution unless you start ripping down ceilings and install plates.

This is the type of application that plates and 8" on center are a must. High floor R-Value.

Smiley

Another Staple up Question

I apologize in advance for the long post. In years past I have done entire homes 4000-7000 sq. ft. that have heated entirely with radiant, those were in bsmt. slabs and main floors encased with litecrete. No Problems!! About 2 years ago I took a job that was supposed to be entirely radiant, but too much$$$, so we've got a primary scorched air system
(our main type of work)and staple up in the kitchen/nook area and the master bath/closet area. The customer was told this was floor tempering only BUT they want it to feel warmer and the heating plant (40 gal. 40000btu gas water heater)hardly ever shuts off. I installed 1/2" wirsbo single loop each joist app. 12" apart and R13 unfaced insulation. The bath area is over a finished basement and would be a bear to get to, the other is over crawl and I found a few of my wirsbo clips broken (weight & gravity?)There aren't any plates and my floor temps are 75 in the bath area and 71-73 in the kitchen area. Both are on floor stats and my leaving water temp at WH is 137 and returning is 114. The crawl has afew small air leaks which will help some when sealed but I don't believe it will cure it. The subfloor is 3/4" ply with 1/2" ceramic board and ceramic tile. The ENTIRE main floor is ceramic with only these two areas heated (radiant)The owner also wants one small area adjacent to the kitchen to have staple up (unfinished above mech. rm.) I'd appreciate any help you can offer.

Smiley

No mixing valve, I faxed system requirements to wirsbo rep in Chicago and he setup system this way.1" Supply out of tank. to combo air purger/expansion tank, then Taco 007? (I believe)to wirsbo manifolds. 1" return to tank. I know wirsbo says their product is good up to 180 deg. What do you suggest for a max. temp. Thanks.

Chris Maderia

I wouldn't

start giving you anything without doing a radiant heatloss and knowing the actual floor R-values and insulation R-Values. I know the tubing can handle 180. All our contractors here use 1/2" and 5/8" Pex for baseboard consistently.

I will tell you this though. Install a mixing vlv, get the water temp in the heater higher and work from there. You need to utilize that return water allowing you to take just enough btu's from the heater to raise that return temp to that 140 degrees. This should keep that heater from running constantly. You also have about 10 degrees of surface temp to play with. See you have very little mass there because there are no plates. I'm willing to bet that you are going to need somewhere around 150-155 degree water to get you where you want to be but that's just a guess based on your info.

One last question? You state that the entire floor is tile, does the kitchen tile foor make contact with any other floor adjacent to it. Shoot the floor around the area where the 2 meet and you will probably find that the adjacent floor(s) are stealing from your kitchen floor. Just another thought.

Bill Clinton_2

more btu's

You need hotter water to deliver more btu's. If your water heater is indeed running all the time and can't get any hotter, it's not big enough.

My personal limit for pex is 160 degrees. That's 'cause I don trust nobody nohow. If you have to exceed that, go for a motorised mixing with outdoor reset so you don't run that hot all the time.

Bill

Chris Maderia

I disagree

40,000 btu's in some cases is enought to heat an entire home with radiant. The reason for the heater running continously is that it's providing 100 percent of the load and he is not utilizing any return water back into the floor allowing the heater to only have to deliver just enough btu's to raise that return water to his desired system water temp. If he installs a mixing vlv and does believe it or not primary/secondary piping he will find that the heater will not be running continously and will recover much quicker.

Poor design from the beginning leading to poor running system, leading to a call back and most importantly leading to a unhappy cunsomer of radiant heat. I learned a long time ago to do all my heatlosses and designs myself because then you have no one to blame but yourself. Reps sell product, good radiant contractors and designers sell systems.

Heatermon

I'm with Bill

If the water heater never shuts off, you are too undersized for a mixing valve to make a difference. If you stick with a water heater, I would try a 50 gallon with 75,000 b.t.u. because with the temperatures you have described, you are alomost there. Then you could add mixing at that point, but we have been sucsessfull in correcting these types of system problems with 150-170 degree water from a high input water heater. It's cheaper than replumbing for a boiler and/or tearing out and adding plates and more tubing (what really should have been done in the first place, but hindsight is always 20/20). Just another reminder of how we can lose our own money when trying to save the customer's.

Good luck,

Heatermon

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Chris Maderia

I again disagree

You can't sit here and tell me that a kitchen and a bathroom are using 40,000 btu's. There is no way. If he installs a mxing vlv and does primary and secondary piping it will stop that heater from running continuously. How many btu's out of that primary loop do you think it's going to take to raise that return water temp 20 degrees. Not very much. The heater now is continually pumping all it's load into the floor, it's not necessary. Look at ther system not the heat source.

Rick_7

Another Staple Up Question

The bath & kitchen have 2 exterior walls each,E&W kitchen,W&S bath, 10 foot ceilings with a lot of glass in each room. The original heat loss calls for 6000 btu, tempering,13000btu full radiant heating, the master suite is figured all inclusive so the bath wasn't figured seperate, the total load was 12000btu.
Also the basement is hooked onto this system which works fine, BUT the owner likes it cooler so the forced air system heats this area 95% of the time.
Yes all of the tile is interconnected & I too have felt this might contribute to the problem. The new area that they are considering is next to the kitchen about 300 sq.ft.with 2 outside walls, N&W. Also BTW looking over my old notes, I asked the wirsbo guy about a three way valve, he replied "NO" Thanks for all the replies, I really appreciate them. Smiley PS. the kitchen area is relatively close to the WH 30-40' the bath is about 50-60' one way.

hot_rod

Chris, whatta smoking

First off 40,000 X 75% is 30,000 output. MAYBE, depends on altitude also. If the heater runs non stop it's out of capacity, period, regardless of how you mix it!

hot rod

Chris Maderia

The Wirsbo guy is wrong

I'd like to hear his solution to this problem. Remember how you arrived at this problem in the first place. Ask your Wirsbo guy what happens when the aquastat fails on the heater and drives 180-200 degree water into that floor. Never, Never, Never run a radiant system without some type of mixing control. Hey, if you don't believe me ask those 57 people in WA state.

Chris Maderia

You can't

tell me that those rooms have a heat loss that high. I don't buy it. No way no how. Something else is wrong and it's in the piping and control. The heaters running because it's continually trying to recover from the cooler water being returned. If he changes his piping to primary/secondary and adds the mixing vlv it will work. Let me ask has anyone tried it? I have and it will work.

Bill Wright_2

Chris,

I agree with you, those rooms should not require 40 MBH ... but where are the Btu's going? If the heat source (regardless of what type) says that it is making 40 MBH & never shuts down, then 40 MBH must be going somewhere. So the questions are: 1) is the heat source really making 40,000 bth? 2) if it is, then where is that energy going?

A mixing valve can not create any energy ... so if the system is currently taking every btu out of the water that the heat source is sticking in, a mixing device will not help.

But, I agree ... the load that you described should not be that large. I think that it is more an issue of mass. The system has no mass for energy storage (except the 40 gal in the water heater -- which, depending on the pump/system, could be emptied in 4 to 6 minutes). Once the water heater is emptied, it must fire to put energy into the return water. The floor doesn't store much energy, so the t-stat should call more frequently than a slab system. Put all that together and I would expect more frequent calls for heat. I would expect that the water heater could keep up & would be cycling off it's thermostat -- sort of like an oversized boiler (but without the iron mass to keep the water temps up when the boiler wasn't firing).

Sorry, I got to rambling -- see if you can figure out what the water heater is "really" making btu-wise, and then find out where those btu's are going ... something in that equation is not adding up.

No sense in adding a bunch of components if the engine isn't able to make the whole thing go!

Bill W.

Heatermon

I'm with you Hot Rod

I can't see the logic in his "mixed" thinking either. One other thing, the number and size of the rooms are just a PART of the equation, there are other things to consider like: When radiant is only for part of the home, there is alot more input needed to the "radiant area" as other parts of the home will "draw off" from this radiant area. I can remember many a battle with homeowners wanting a 90 degree Master bath area and then complain that the adjacent bedroom is too hot at 75 degrees. But bottom line is, water heaters only heat at one speed and if they are constantly running, the unit is undersized for that application. You need to lessen the load or increase the fire power to make it work.

Heatermon

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Smiley

A bit more info,this is central Indiana,last year was pretty mild and he swears itworked great,this year much colder,avg.25-35 high 10-20 low sometimes above,sometimes below, anyway he's not been happy this year at all. The only possible "change" I can think of is perhaps the tubes coming loose out of the clips. Thanks again.
Also if I do install a mixing valve, is primary/secondary piping required?