Help with infloor heat

Tom99

Hello everyone, just wondering if I can get some guidance with my infloor heat. My apologies in advance for lack of terminology. I have a 5 loop system and my concern is that the floor doesn't feel as warm as it was before. Also the flow rate seems a bit low. I have included some pictures maybe someone can guide me in the right direction if there is something wrong with the system. Thanks everyone!

Tom99

Sorry i also should have mentioned that only the garage is on glycol and there doesn't seem to be an issue there. The basement is on water

GGross

The pump appears to be on the wrong side of the mixing valve. But this all worked well for years before I assume? floor is feeling slightly cooler, hows the air temp in those spaces?

Tom99

Hey thanks for the reply! Yea the floor seemed to be working fine until last year which is when I noticed the floor doesn't feel as warm as it did, so I had the floor flushed and refilled with fresh water at the beginning of this year's heating season but still seams the same. Air temp is at 68.9f. I've had two mechanical contractors in here and none of them mentioned anything about the pump being on the wrong side of the mixing valve

Tom99

Don't know if this makes a difference but the boiler also does domestic hot water and the furnace

Jamie Hall

I agree about the pump and the mixing valve. Not quite sure, in fact, how that is supposed to work.

However, if it worked before… can you change the temperature of the water going to the floor by adjusting the mixing valve?

Tom99

Thanks for all the info guys I really do appreciate it! I could adjust the mixing valve but in this case does it even make sense to do that considering the pump is installed wrong? Here is a pic of where the mixing valve is set to now

hot_rod

Your best tool to troubleshoot is the temperature gauges on he supply and return. 120F would be a reasonable supply, the return would tell you how much temperature drop through the loops.

I agree the circulator should be on the M mix port pulling from H&C ports

Many three way mixing valves have screens on the H&C port, under those connection niuts. As they plug, flow is reduced, output decreases.

I'd guess you want to see around .5 gpm per loop?

Screenshot 2024-12-19 at 2.39.47 PM.png

Tom99

I have had the screens cleaned on the mixing valve they weren't that. I have the same temp on the supply and return 120f

DCContrarian

If it was working and stopped, you want to figure out what changed. Ultimately it's going to be one of two things, either the water temperature or the flow rate. We're not going to know what they used to be. There really isn't such thing as "normal," there's a range of values that can work and they vary pretty widely. These systems are basically hand-built.

So far I haven't seen anything that looks way outside of the ordinary. I'd say the water temperature is on the low end of the range but not totally unreasonable.

What's almost certainly not going to work is just changing things randomly. More likely you'll just make the problem worse.

Do you have any plans or engineering documents that would give a clue as to how it was meant to perform?

Tom99

Thanks for your input! Unfortunately I don't have any info on how the system was installed. Some other members have mentioned that the circulating pump is plumbed incorrectly I suppose I should start there. I can't seem to get the flow any higher as the flow meters are fully open.

DCContrarian

https://forum.heatinghelp.com/discussion/comment/1827998#Comment_1827998

Since it worked for a while I would ignore that. Fixing things that aren't broken just makes the situation harder to diagnose.

I'd be focusing on what the flow is in each loop, what the temperature drop is, and then trying to figure out what they should be. I they're not where they should be, then trying to figure out why not.

Are these loops the only source of heat for the house? What's the boiler rated in BTU/hr? We can start off by trying to estimate how much heat the loops should be delivering.

DCContrarian

If the symptom is "the floor doesn't feel as warm as it was before," I have to ask if the system has outdoor reset (where the water temperature adjusts according to the outdoor temperature). Could it be it's working as designed, it just isn't very cold outside?

Tom99

I also have a furnace for a heat source. Here is the rating plate on the boiler

Current flow rate is 0.15 gpm across all five flow meters

Tom99

How do I know if the system has an outdoor reset?

Tom99

Sorry this is all new to me

Tom99

I looked up and outdoor reset my system does not have one

hot_rod

,15 gpm is the issue. My money is on a plugged mix valve.

Here is Caleffi’s opinion on mixing valves used for hydronics.

IMG_0893.png

DCContrarian

https://forum.heatinghelp.com/discussion/comment/1828041#Comment_1828041

Agree on both points. It may be as simple as turning the knob back and forth a few times to loosen it up. Note the setting before you start.

Tom99

Hey hot rod I had the mixing valve apart and the screens were clear. As suggested earlier I should probably get the mixing valve replumbed and that quick read you sent suggests the same thing

bjohnhy

Are all your radiant distribution not heating well or just those within the mixing valve (slab floor only)?

Mixing valve is highly suspicious. I agree it is not piped ideally. There is no way it can mix that way. They can go bad, and if yours did it could be pumping in loop through the cold inlet. How old is that mixing valve?

Can you use a portable temp probe to check the supply and return temps as it comes out of the floor/manifold?

What is the temp coming out of the boiler?

Tom99

The only radiant heat i have is in the basement slab. The whole system is 4 years old. I don't have a temp probe but I can try and get one. The temp out of the boiler is 140f and as mentioned before the supply and return are both reading 120f

Kaos

I'm pretty sure the mix valve can't work like that. I think what was happening before is the loads before the floor heat drooped the primary loop temperature enough that the mix valve was near fully open. In that case, the location doesn't matter as the water flows straight through.

My guess is something changed on the loads or the flow in the primary loop increased which is now causing the mixing valve try to do its mixing thing, but in that plumbing orientation it simply restricts the output of the pump.

Re-plumb the mix valve where it needs to go and it should fix your issue.

bjohnhy

In theory

bjohnhy

You can try turning the mixing valve to hotter or hottest setting, once you get a baseline temp in and out of floor. But that could intermittently make your floors too hot?

Otherwise, I would do what Kaos said

Tom99

Thanks alot guys for all this info. bjohny thanks for that markup pic it makes sense on what is happening. If it's not too much trouble can you do a mark up of how I should plumb it as I'm going to try this myself lol oh boy

bjohnhy

I'm sure there are some good diagrams around. But first, tell us what that 1st Recirc is going to?

2nd pump goes to slab in question. 3rd recirc goes to heat exchanger for garage.

Tom99

First pump goes to the furnace, second pump floor, third pump heat exchanger and fourth pump garage manifold

bjohnhy

Are you by chance using the furnace a lot more this season than last?

Dave Carpentier

So the forced air furnace part… does that blow into the basement too ?

Maybe airflow changed to cause more air into the basement and the slab heat reduced its calls ?

Tom99

No not really it's only -6 here in Canada eh.

Tom99

Yea the furnace blows into the basement as well. I thought the same thing Dave so i left the furnace off purposely to see if anything changed with the floor and it didn't

DCContrarian

https://forum.heatinghelp.com/discussion/comment/1828075#Comment_1828075

Canadian or American degrees?

Tom99

Lol Canadian

Kaos

Your snow melt mix valve is also in the wrong spot.

Tom99

I also questioned that after you guys gave me the info on the floor thanks Kaos

Kaos

I think plumbing fix best left to after the heating season.

For now you can leave it as is. If you want to try something to get more heat, you can set the floor heat mix valve to max and adjust how hot the slab is by turning down the flow to each loop on the manifold. Depending on how hot your boiler water is, you'll get some striping and the slab near the manifold will be hotter. By turning the mix to max it will open all the way and you should get more flow to the floor heat manifold.

Tom99

Hey Kaos I think the mixing valve is already at max, and the floor by the manifold is really warm. Now it's really bothering me that it's plumbed wrong I have to get this changed ASAP. Would it be possible to just mark one of my pics up so I can follow something with no second guessing myself

Tom99

Also since this problem i am going through propane like crazy

hot_rod

plenty of room under the mix valve to move the pump down there.

build a spacer to replace the pump where it currently resides

You have enough isolation valves to make it an easy correction

Tom99

Thanks hot_rod! I guess I was kinda overthinking it. I'm gonna give it a shot over the break