Coaching required -

Jorgy

I’m in 2000 sq ft 18 year old house, slab on grade, built for us. Closed system, In-floor radiant heat, 4 zones, 4 manifolds, 1/2” Uponor Pex, Tru flow Jr manifolds, Taco 007 boiler, two Grundfos single speed pumps, HTP boiler 120k . House was insulated to code, 2 x 6 walls, etc. As seems to be common, when it gets the coldest (MN), it doesn’t keep up. I have struggled with one zone (3 loops) since a few years after it was new. The zone only satisfies when it’s in the 30’s. I added flow gauges to this zone and have been doing some “controlled” experiments making some assumptions about which loop is the longest, opening it up fully and playing with the other two, reading temps and trying to achieve a 10-15 degree delta. It did satisfy the thermostat but again, only when it was in the 30’s. Now it seems this thing is running all the time. It also seems that more heat is near the area of the manifold which wasn’t the case before.
It has been cold but I have come to the conclusion that it still isn’t balanced or the pump is underperforming after 18 years. I am thinking I need a design company to reverse design this system so I know what I have (longest loop on this zone) and can set things correctly. Is it worth the money to do that? I have the floor plans and I have a number of photos so I am guessing they can get close (along with an infrared camera for location of loops). I don’t have heat load calculations but I probably can get them from the architect. How would you guys handle it? How is me tweaking this zone affecting the other 3 zones which I haven’t touched? Your thoughts on where to go from here would be appreciated. Thank you!

Larry Weingarten

Hi, Might it make sense to have a good look at everything (system and shell of the house) using an infra-red camera? That way you'll know where the heat is going, and will have concrete things to fix. Also, I'd consider installing flow meters, so you have that data and know which loops aren't flowing properly. Knowing historic energy usage would help too. Finally, using a blower door to see where the heat is going, could be useful for getting to the big leaks and reducing the load. Meeting code is nice, but is a low bar when it comes to energy performance.

Yours, Larry

hot_rod

are there any y strainers on the system? Over the years they can get restricted and cause under performing issues

If you can find the original design you would know what temperatures are required

EBEBRATT-Ed

It's possible you need a little larger pump although if one area is under radiated that will not help. You could play with the flow rates a little to see what works best. Slower flow may give you more heat transfer but will give you a lower average water temp.

mattmia2

Did it ever work right?