Many years of issues with radiant floor heat.
Comments
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So is the boiler at 140 or are the zones seeing 140?
There is no hydraulic separation as required by Laars. That weird bypass with the throttled valve between the two tees is something that is often done with high temp boilers in low temp systems, but that is not the case with this system and it should be piped per the install manual.
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You could have a plain uninsulated water tank in your basement that stores and is fed by your well. The Laars dhw could draw from it. It would then have basement temp water. OR…you could have an insulated tank with electric elements that keeps it at…"whatever"…60°, 75ª, or 120°! Help out the Laars.
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The Laar's hits 142-145 and each zones thermometer is reading around 140 on the supply side of the circulator.
On your comment "There is no hydraulic separation as required by Laars" weinitiallyy plumbed it per the Laars drawing and then added the valves to get the system to circulate. if both of the valves you see in the photo are open, the supply temp at the circulators drops. I leave the left valve open some to recirculate back to the Combi and keep the right valve closed. When we got the Laars we installed per "I think" their drawing here. If its wrong, let me know what needs changed and will it somehow help my issues.
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One other fact is, the Great room is behaving now the same as when it was plumbed as an open system with a hot water tank, making think its not a Laars configuration issue.?.?
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I really think getting the water temp raised would help a lot, but unsure if its safe to do with the tubing I have. If I recall correctly, when Ive shot the floor with an IR gun, I see the temp in the upper 70's at the tubing location as I scan it across the floor.
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Personally I would just raise that water temp up 10 degrees to start, you might get some squeaking . Since you have the IR gun if you follow the tubing path you don't find any big sections noticeably colder? I know you have wide spacing so the space between the tubes will be colder, just want to see if the tubing is transferring heat evenly in the places it is actually located.
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#1 issue: great room is not warm enough when <20F out.
I see the pictures.
A few f/u questions
Have you ever had a blower motor test to check how leaky the house is?
Is your great room floor uncomfortably hot in areas?
What is all the material in the great room floor, between the 7/8" loop and the room? 3/4" plywood", then hardwood floor? any big rugs?
What is the temperature in that basement room that is "unconditioned" when it is <20F outside?
Does your boiler and circulators run continuously , 24hrs straight, when the temp is <20F outside?
What is the model on the B&G circulator for Great room?
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Have you ever had a blower motor test to check how leaky the house is? No, I assume its pretty tight and built with 2x6 before it was required and windows wraped with ice & water prior to siding. Whole house was new Anderson windows. Not even sure what a Blower motor test is and what the fix once you get negative results?
Is your great room floor uncomfortably hot in areas? No, uncomfortable cool 60* in great room on cold nights.
What is all the material in the great room floor, between the 7/8" loop and the room? 3/4" plywood", then hardwood floor? any big rugs? The 7/8" tube stapled to sub floor/wafer board. On top of sub floor in nearly all first floor is prefinished hardwood, probably 1" thick tongue & groove.
What is the temperature in that basement room that is "unconditioned" when it is <20F outside? 56*F
Does your boiler and circulators run continuously , 24hrs straight, when the temp is <20F outside? Yes, matter of fact, the great room is attached to my mid section/dinning kitchen area with 8' ceilings. I set each stat at 80 last night, since the mid zone will satisfy, figuring it could help the great room. Then I set the Mini Split to 70. Woke for work and the house was a perfect 70* this morning and all floors toasty. Mini Split humming along on low. Master BR set at 65 and cycles on & off no issues. Mid section set at 68 will cycle on & off, the great room pretty much runs non stop everyday below upper 30's outdoors all winter. GRRr.
What is the model on the B&G circulator for Great room? I will have to look.
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I mean the floor, after that zone has been running 4+ hrs, when you step on it, is it too hot to the feet in the great room?
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Never, ever too hot to step on, anywhere in the house let alone the great room. Here is the pump feeding the great room.
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It's unfortunate but it really seems the issue is a poor design. You would likely get a little bit more out of the floor by insulating and bumping the water temp up a bit but I think the floor is giving all it can or very nearly so. I'd add some emitters. Because the tubing is a non barrier type, or I imagine it is, any added emitters will have to tolerate oxygen to some extent. The other alternative is to start over with a more complete radiant layout. Your place so reminds me of a job I was asked to look at some years ago. Same thing, great room under performing. I did a heat loss and floor design and came up with a number far greater that what was installed (RT single run in the joists with a water heater) and the space barely reached 60*. In fact the there was not enough floor to satisfy the space and to reach a comfortable set point even with a sound design, there would need to be added emitters. Not what the home owner wanted to hear after spending what they did on the system in the first place. It's a tough spot to be in.
Miss Hall's School service mechanic, greenhouse manager, teacher, dog walker and designated driver
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I think that temp limit was when running an open system at DHW pressures. On a closed system you are probably at 20PSI max so way less. I don't see issues with a couple more F especially if the floors are never too hot.
I have tried running hotter water into a heated slab before. Besides getting some stripping, there was no issues with it, thermostat was would just be satisfied more quickly. You do have to watch not to overheat the surface though as that is certainly possible if allowed to run without some control.
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Mr Coldhouse,
Are you 100% confident that Great Room circulator is circulating? Those thermometers could be showing the temps you describe with just migration from the header. A rudimentary check is to slowly close that ball valve above the great room circulator and listen/feel for turbulence. Don't close it more than a second.
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Take a look at the tee orientation in the Laars drawing versus what you have. The boiler should enter and exit the branches of the tees, while the runs of the tees have unobstructed flow through the emitters. The way you have it, especially with the bypass valve throttled, your boiler circ and zone circs are in series and you have no hydraulic separation.
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while your piping is not ideal, I doubt changing it will correct your issues
Piped like that you still get flow to the boiler to keep it happy., flow wise
Someone has even chocked the boiler loop down adding some of the boilers pump flow to the zone circs, probably to no effect
Keep researching the tube, Im unaware if any PE that cannot take 180f at that pressure
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
As others have pointed out, the boiler is not piped correctly. The supply and return headers are tied together at the ends. It is not primary-secondary piping. Return water bypasses right back into the supply headed. This mixed flow reduces the supply water temperature.
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I'm with Hot_Rod. The issue here isn't boiler piping. If anything it is similar to how some of the Euro modcons are plumbed with TRV rads.
The issue here is you are not getting enough heat into the room since the floors are never warm enough. With heat spreaders you should be able to overheat that floor at your boiler supply temp.
Can you access the joist bays under the room? If you reach up above the bubble wrap near the outside walls, is it cold there?
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Definitely not starting over. The system works fine 95% of the outdoor Temp range. What are emitters?
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The pressure gauge on the Laars Combi says 12PSI. So your line of thinking is the 150*F max hand written on my spec sheets is for my system when it was using 55-60 PSI domestic water pressure. If the tubings temp rating changes that dramatically when using lower water pressure, can I safety try running the Laars up to 155-160* and see what improvements occur? I am today going to get eyes on the actual tubing and see what is stamped on it. We have a Arctic Front moving in here Sun-Wed with high temps here predicted to be in single digits with overnight lows below zero to possibly -20. I would like to jack the Laars temp up before that.
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Yes, 100% certain it is circulating. I have throttled down the supply valve and heard the cavitation noises.
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I’m on tubing check duty today after work and will report back.
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I will check the joist bay temps while check the tubing tonight and report back.
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95% ain't bad, better than some. An emitter is simply another radiator or convector, some other source of heat to get you over the hump so to speak.
Miss Hall's School service mechanic, greenhouse manager, teacher, dog walker and designated driver
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I am going to draw a diagram of what I have now and also of what it should be and I will post later to confirm I completely understand.
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Here is a detail of a way to seal all your exterior rim joist. The rim joist is the framing member that goes all the way around the building, it sits on the foundation.
The wood shrinks or cracks with age and allows the heat to escape, or wind and cold to enter. Known as infiltration.
Buy a sheet of 2" foamboard at the lumber yard, cut it a bit smaller than the space and use those cans of spray foam to seal it in place. Then a 6" fiberglass piece also. If you can do the perimeter of the home, this can make a big difference.
I would spend money on this idea before you change anything on the system piping, tubing, etc.
Contact the company that supplied that tube and ask for the spec sheet, they should know the data? They didn't extrude the tube, it is private labeled from some tube extruder.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
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With what you have now, if you open the bypass valve all way and close the valve at the end of the loop, you have exactly that diagram.
I would not mess with something that is running well as is. If loop supply temps are the same as boiler temp and boiler return is loop return, it is running well.
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You have a primary loop IF the ball valve at the right hand side stays closed.
I'd open the ball valve on the left side cross over wide open.
Here is the flow path of the primary loop that you have. The tees are not textbook "closely spaced tees" but the boiler has a flow path, adequately sized to keep it happy.
Yours is a variation of fig. 6-4. But with the tees being used in a different orientation.
You bottom drawing is the best, assuming it meets the dimensions.
What you have will work just fine, don't waste money repiping it.
The Heatway HydroControl panels were piped with the secondaries out the run of the tee like you have. Thousands of them were made, installed and worked fine.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
A classic Holohan saying, "what goes into a tee, must come out of a tee"
Assume your boiler has a circ inside moving 8 gpm, 140F is leaving the boiler.
At your primary secondary connection, one zone is running, it is moving 4 gpm to that zone.
So the cross over now has 4 gpm going through it. As the return piping connects back in at the bottom, 4 gpm to the zone blends back with 4 gpm from the boiler and you have 8 gpm going back to the boiler.
The boiler always has 8 gpm going through it. This is the gist of primary secondary piping. The best explanation is in this book Primary Secondary Made Easy, buy it if you want more explanation. With a bit of humor :)
This system should have the boiler or system sensor strapped to the piping before the zone circulators.
As those flows mix, temperature is changed. The sensor will respond and raise the boiler output to assure you actually get 140 at the zone circs.
Judging by the partially closed bypass ball valve, temperature adjusting, as it is, is being done manually. Also inaccurately.
Pumps deliver flow, measured in gpm
Boilers deliver temperature, measured in degrees.
You need to have both in the proper proportions for eveything to work properly.
As stated by others, your constipation is in the tubing application. But with a few corrections, temperature assurance, you may overcome the constipation. System constipation, not you personally :)
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
I remembered, I have a roll of it left in the barn. Here’s the pics of the tubing.
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can’t make up the dismay in seeing the manufacturer.
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Generally the pressure and temperature is stamped also. Look further down the tube?
If not look up the ASTM D 3350 file. I think That standard was for metric size tube.
You can contact the PPI directly at their site.
Lance the PPI director stops by here from time to time.
You may be correct about the 150F !
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
here is a post I found searching the internet that came from this forum.
https://forum.heatinghelp.com/discussion/63667/radiant-heat-piping-have-you-seen-this-pipe
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