Radiant Heating Help

turbosl2

System/House Specs:

3000sq ft single story (above grade)
2000sq ft lower level (basement)
Bryant BW9 Boiler (Set temp ~175)
1/2" Pex (orange/red color)
Aluminum Diffusers installed at doorways
6 Zones (Argo Controller) w/ 6 valves
Single Circulator pump
Brass Manifold w/ball valves (no flow meters)
Hardwood & Tile throughout
Spray foam at all sill plates
Bat insulation under all floors

My father in law is having some issues with the radiant heat keeping the house warm. Its new construction and the house was originally designed with forced air, then radiant heat added later. The system was designed and installed by him. All rooms above grade do not seem to reach target temp (68), they consistently remain 1-6 degrees under. Outside temps are -10 right now. The zones are not all equal 300ft runs, some are 2-3 times longer runs than others. It appears the longest run (great room, kitchen, study) is 67 which is closer to the boiler. The Master bedroom and bath are at 62, this is the farthest run from the boiler but a shorter run overall compared to the great room. All valves are open

Jamie Hall

For radiant to be designed -- and then installed and work properly -- you need to start out with a room by room heat loss calculation. Then you can figure out whether or not you can meet that with radiant and how the radiant should be laid out and what plates etc. to use.

Was that all done?

And 175 is way too high for radiant heat -- 110 to 120 at the top, to avoid damage to the flooring...

turbosl2

> @Jamie Hall said:
> For radiant to be designed -- and then installed and work properly -- you need to start out with a room by room heat loss calculation. Then you can figure out whether or not you can meet that with radiant and how the radiant should be laid out and what plates etc. to use.
>
> Was that all done?
>
> And 175 is way too high for radiant heat -- 110 to 120 at the top, to avoid damage to the flooring...

I believe all that was done. The system was self installed then a contractor paid to come and hookup the system. I think there was a disconnect because the heating company made a manifold with ball valves, didn’t use a hydronic manifold. No way to monitor in or outlet temps at the lines, just at the boiler. No way to throttle or balance the system or check flow either. Seems strange! Thoughts. The temp I provided is at the boiler, shut off point. Cycles to 180, 5 mins later drops to 140, process repeats. I am trying to upload a link to an image

turbosl2

Pics of the system

Brewbeer

Any photos of the underfloor piping ?

hot_rod

any carpet or throw rugs in those rooms? Bed with a dust ruffle?

You need unencumbered floors to get full output. Design conditions put that to the test

GroundUp

Are all zones in fact getting hot water? Sounds like some may be airlocked. As was mentioned, 175 is WAY too hot for underfloor. If a proper heat loss calc was done, this wouldn't be an issue. There seem to be a multitude of issues here. Were transfer plates used? How thick is the subfloor? What is the finished flooring?

Gordy

“Aluminum diffusers installed at door ways”

What does that mean?

Sounds like a suspended tube, or plate less staple up design with those water temps.

Tile, and hardwood through out.

Is the basement radiant in concrete I assume? Has no trouble keeping set point?

I don’t see a mixing valve, and that’s a problem. Pex is rated at 180* but you’re concrete basement floor should be no more than 110.

turbosl2

> @Brewbeer said:
> Any photos of the underfloor

No and it’s all Sheetrocked in most of the house

Brewbeer

turbosl2 said:

No and it’s all Sheetrocked in most of the house

There doesn't seem to be any sheetrock on the ceiling above the boiler. Can you pull down a section of insulation there and take a photo of what was installed?

turbosl2

> @hot rod_7 said:
> any carpet or throw rugs in those rooms? Bed with a dust ruffle?
>
> You need unencumbered floors to get full output. Design conditions put that to the test

> @hot rod_7 said:
> any carpet or throw rugs in those rooms? Bed with a dust ruffle?
>
> You need unencumbered floors to get full output. Design conditions put that to the test

A few small throw rugs over hardwood. Very minimal
3/4” osb with 3/4” oak hardwood or 1/2” hardibacker with tile

Basement is heated by baseboard around the perimeter nothing imbedded in concrete. All pex is stapled between joists not embedded. Diffuser plates only in cold zones such as doors.

The interesting thing is there appears to be a custom manifold with no temp meters or flow meters, ball valves for meter flow. Seems crazy and impossible to adjust since there is no data to go off of, except using a infrared thermometer.

All zones except the basement are getting hot water. Basement is off since it’s only used for entertainment on occasion. Each zone is on and return pipes are hot, almost can’t touch them.

DZoro

You should have approx. 6000 ft of tubing, is that what you have? Tubes spaced 6-8", two per 16" joist pocket.

D

Gordy

I see why they are running high SWT if there is only plates by doors, etc. it’s a basically unplanted staple up it seems from the discription using the same water temps as the baseboards.

turbosl2

> @DZoro said:
> You should have approx. 6000 ft of tubing, is that what you have? Tubes spaced 6-8", two per 16" joist pocket.
>
> D

I think it’s close to that in total tubing and yes 6-8” between joists. Is the manifold a concern and no mixing valve, flow meters...etc

turbosl2

> @Gordy said:
> I see why they are running high SWT if there is only plates by doors, etc. it’s a basically unplanted staple up it seems from the discription using the same water temps as the baseboards.

Correct.

What is everyone’s thoughts on resolving the issue. I was just informed this morning that he restricted the greatroom zone with the ball valve to aproxcimatly 45deg and the entire house equalized at all thermostat set temps of 68. However I am not confident this will work long term.

DZoro

At this point the manifold probably is the least of your worries. Are all the tube lengths <300' ? Is there any foil just below the tubing, and r-19 below the foil? You should have approx. 20 supply tubes and 20 returns? Can you post a picture of those manifolds?
D

Gordy

Well if you are using 175 swt, and losing ground on setpoint. Are you sure loops are purged of air, and all loops have flow. Manifolds with flow meters, and valves are great visual indicators. if the loops are with in 10% of each other for length balance shouldn’t be an issue, there are plenty of successful installs which don’t use them.

You could use an infrared temp thermometer to check the individual loops supply, and return temps. Running 175 though a good hand feel will tell you if loops are flowing.

Gordy

I see 6 zone valves..........

Gordy

Looks like the valve at the boiler tying the main supply, and return together is an attempt at mixing. Need to know the supply, and return temps at the manifolds. The boiler may say 175, but the manifold could be less.

DZoro

Or attempt at primary secondary. Not familiar with that boiler but it looks to be condensing.
What is the model of the boiler?
New install I'm guessing, good chance of a air locked system.
D

hot_rod

Got the load calc data handy? Realistically figure 15 btu/sq ft output from a dangled Pex installation.
On cold days, rooms with higher loads will fall behind the t stat set point, generally.

https://www.pmmag.com/articles/89003-shakeout-time-br-john-siegenthaler-pe

turbosl2

> @DZoro said:
> At this point the manifold probably is the least of your worries. Are all the tube lengths <300' ? Is there any foil just below the tubing, and r-19 below the foil? You should have approx. 20 supply tubes and 20 returns? Can you post a picture of those manifolds?
> D

The tube runs are all over the map, none are maintained at 300. I would guess some 3x others. 4500 + ft of pipe on six zones. I am not sure if there are headers within each loop. The only manifolds i know of are shown. I will get more info tomorrow. Yes I believe reflective foil under pex before the bat insulation

turbosl2

> @Gordy said:
> Well if you are using 175 swt, and losing ground on setpoint. Are you sure loops are purged of air, and all loops have flow. Manifolds with flow meters, and valves are great visual indicators. if the loops are with in 10% of each other for length balance shouldn’t be an issue, there are plenty of successful installs which don’t use them.
>
> You could use an infrared temp thermometer to check the individual loops supply, and return temps. Running 175 though a good hand feel will tell you if loops are flowing.


I can stop over and get this info tomorrow. All loops are def flowing except baseboard in the basement which is turned off. That is the only pipe I can hold.

Run lengths are for sure not within 10%. Some are 2-3x longer due to the room being larger and everything goes into each of the zones. I will ask if he has headers within the loops

DZoro

So are some of the 1/2" loops 900' long?
D

turbosl2

> @hot rod_7 said:
> Got the load calc data handy? Realistically figure 15 btu/sq ft output from a dangled Pex installation.
> On cold days, rooms with higher loads will fall behind the t stat set point, generally.
>
> https://www.pmmag.com/articles/89003-shakeout-time-br-john-siegenthaler-pe


Yes I think he has the calculations. I will get that info as well. Question is where is all the heat going because it’s not going in the basement insulation seems the keep it in the cavity and warm the floor.

turbosl2

> @DZoro said:
> Or attempt at primary secondary. Not familiar with that boiler but it looks to be condensing.
> What is the model of the boiler?
> New install I'm guessing, good chance of a air locked system.
> D


It’s a Bryant BW9. Yes new install 3 years ago but it never worked perfectly. Finally getting around to helping diagnose the issue. Forced hot air is the main heat source if radiant can’t keep up or is all over the map like it was the other day. Just shut er down and forget it. Fire back up on a warmer day. That was the approach

turbosl2

> @Gordy said:
> Looks like the valve at the boiler tying the main supply, and return together is an attempt at mixing. Need to know the supply, and return temps at the manifolds. The boiler may say 175, but the manifold could be less.


That valve is now closed and the temp went up from 52 to in the 60s. I will gather data tomorrow

hot_rod

Correct, that is the mechanism that transfers the energy from the hot supply fluid to the room. Warm the air in the space which in turns warms the floor surface.

But air is not a great conductor of heat energy, especially in a closed, insulated bay.

Floor covering r value compounds the constipation of heat transfer.

If the system Works acceptably on mild to moderate loads and falls behind as load increases, it is probably a distribution bottleneck. You may be at the end of the road without adding supplemental heat emiuers.

Try all the suggestions above, tweak where you can, do all you can to lower loads, window coverings, etc.

Gordy

Couple things come to mind. Maybe the forced air was part of the design as a supplement to the radiant with very cold temps.

If that center valve is now closed you will deffinetly be sending boiler temps out to the system which is why you are gaining set point.

Is the owner using set backs?

turbosl2

You guys have been a great help so for, i really appreciate it.

I made some mistakes in info above. The ENTIRE system has diffuser plates. The plates are finned and pex snaps into it.

The system was designed to be the sole heat source. The forced air was installed for AC but an entire furnace was installed as a backup due to minimal added cost.

Center valve is now closed completely. All rooms seem to be maintaining their set temps now that the largest run (great room, study, kitchen) was throttle back on the ball valve.

No setbacks, constant 68deg

Even though all rooms reach target it appears the system still continues to call for heat on all zones and boiler continues to run, cycles on and off every 2mins or so. ~175, 2mins go by and it hits 140 (temps at boiler), lights, heats to 175...process continues. All zones running. I will get temps with infared thermometer tonight.

Circ Pump:

TACO Model V007-F5
1/25 HP
.71Amp
3250RPM
125PSI max
240deg Max
Class F

Should i install a 6 zone flow control manifold and thermal storage tank. If so which one is recommened?

hot_rod

check floor surface temperatures when you get a temperature gun. You should limit the surface to the low 80’sF. Above 83 or so the floors become uncomfortable and excessive temperature may damage the wood flooring. The RPA publishes a Flooring Guide for radiant installation which has good info

DZoro

If all the rooms reach target, the boiler should shut down completely. Check control wiring.
Something needs to be looked at with that center loop, air, short loop/s....
Is there foil under the fin plates?
D

SuperJ

The manifold is ok, and seems decently made. I wouldn't consider replacing it. Throttling ball valves is an acceptable way to balance, but you could cut some Caleffi quicksetters in to confirm and precisely adjust the flow (they are balancing devices with a built in flow gauge).
https://www.caleffi.com/usa/en-us/catalogue/quicksettertm-balancing-valve-132432a


I suspect you either have a pumping or balancing issue. You can measure the temp delta with an IR thermometer/ or a contact thermometer (wrap the pipe with some sort of black tape first though). The temp delta will give you an idea of where the heat is going. You can then throttle the loops with the lowest temp deltas/highest room temperatures to free up more flow for the worst zones.

You could install some hydronic thermometers on the return lines (no need on the supply since it should all be the same).

You may need to consider a different pumping arrangement if the flow rate is too low. I suspect your boiler may be oversized, adding a buffer tank between the boiler and zones would help tame the cycling, but figure out your flow issues first. Do you have the design flow rates, temp delta's, and pressure drops for each zone and the whole system?

SuperJ

Also, is there proper insulation under the diffuser plates?

One other thing that might be affecting your flow is I see a lot of the non-expanded insertion PEX barb fittings? With PEX generally you should try and bend rather than use 90deg fittings. There a 90deg bend supports you can get to prevent the pipe from kinking or collapsing on a tight radius bend.