Best option to fix a Radiant floor that's cold on one side?

Heatwave1

Not sure the year on this post but did you remove the return manifold stem assembly to make sure it’s good. Some manifolds if turned off to tightly leave the o ring or washer behind and that could hamper the flow. You could do the same on the supply side too. 

mikespipe

you mentioned a CI radiator it makes me wonder if you have rust or debris clogging a loop or Y strainer . also are the feed and return loops reversed on the manifold that can affect the balance of the system. they should be reversed to balance the flow. lastly i see a lot of very good advice , this site is the best.

Glenn_Venco

Apparently, this is a very minimal flow as indicated by the IR photo. That would seem to indicate you are not airbound. If there are power heads on the loops, remove the head on the loop circuit that is not heating. You'll probably find it is not working - either a bad wire connection, and/or simply NG.

TAG

I'm confused .. are you telling us that the boiler has outdoor reset and it's set up and working ? You have mixing valves ? And you have a thermostats in the rooms controlling the zones?

If this is all radiant ...

If this is true you need to open all the zones and valves and put it on constant circulation -- let the boiler control the water temp to the largest area. Unless you have long run times the floor is never going to have uniform temps. With reset you don't need the mixing valves ... it's screwing things up. The boiler is able pick the water temp ... even if the outdoor sensor is not in an ideal position it will still have the relative temp swing .... it just takes some time to get the boiler tweaked. Once you get the main area dialed in you can then dial back the areas that may be getting too much flow .... it here that you may have to use a thermostat.

I always zone my houses and with a small room you sometimes have to use a thermostat as a high temp limit as even with low floor they can over heat (especially with sun factored into some spaces) .. typically with a bathroom I don't care if they are the hottest rooms. I run wires for the thermostats just in case they are needed. You have to start with the area needing the hottest water. With the Alpha pumps set on auto they make it easy to set these up ..

If you have radiators ... that's going to change things .... but -- I have set up an old house with CI radiators on reset. Now you need a mixing valve for the radiant .. ideally a second controlled by the boiler

Roobul

4Johnpipe said:

Issues can only be flow, insulation below or air.

There is 10"-12" of open cell spray foam under the floor. Walls are foam, too. Windows are brand new. The issue is flow, the question is why. From all of the above, it seems most likely that the Taco mixing valve is restricting the flow preventing the pump from working to its potential.

Roobul

SKYPAINTER said:

Is the pump installed on the "mix" side of the 3-way or is it pumping "into" the valve? Always want the pump on the mix side, pumping away from 3-way.

The pump is on the mix side, pumping away from the 3-way valve and into the manifold.

Roobul

propmanage said:

If you close off the hot loops do the cooler loops heat up. Are you sure you have no air?

It's not so much that I have hot loops and cold loops - it's more that the longer loops are "cold" by the time the water returns, so the floor temp above one given loop is uneven (Delta T can be as much as 35*). It's most noticeable on those loops on the 5-loop zone. If I shut 4 of those 5 valves, the remaining loop heats up more evenly (and Delta T drops).
I am not sure I have no air. Since I have glycol in the system, I assume I'd need a high pressure pump to recirculate the coolant from a reservoir (bucket) to purge the system, or a good plumber ;-)
I do have a Caleffi SEP4 low loss header, which supposedly purges air pretty well (if it passes through it).

Roobul

4Johnpipe said:

Pictures of the near boiler piping are needed.

Roobul

Glenn_Venco said:

Apparently, this is a very minimal flow as indicated by the IR photo. That would seem to indicate you are not airbound. If there are power heads on the loops, remove the head on the loop circuit that is not heating. You'll probably find it is not working - either a bad wire connection, and/or simply NG.

If by "power heads on the loops" you mean the actuators or flow valves on the manifold, yes I have them and they all open when called. I do have flow through all loops, apparently just not enough.

Roobul

TAG said:

I'm confused .. are you telling us that the boiler has outdoor reset and it's set up and working ? You have mixing valves ? And you have a thermostats in the rooms controlling the zones?

If this is all radiant ...

The plumber did not install the outdoor reset sensor when he installed the boiler. I added it this winter (December). It is working, and the zone target temps vary with the outside temp.

I do have a Taco 5000 mixing valve for the radiant manifold (its CV is 2.3 which may be the issue or part of the issue).

I have 6 Azel thermostats (bedrooms, living/kitchen area, bathrooms). They're set to regulate air temp with a floor sensor set as a high limit (in case the mixing valve fails).

I have other non-radiant zones: 1. Indirect DHW, 2. Modine Hot Dog H2O, and 3. a small cast iron radiator; hence the mixing valve.

When only a radiant zone is calling, the boiler target drops to ~110*F and when one of the other zone calls it cranks up to 160*.

Re. your last comment: "Now you need a mixing valve for the radiant .. ideally a second controlled by the boiler" -- what does that last part mean?

Roobul

mikespipe said:

you mentioned a CI radiator it makes me wonder if you have rust or debris clogging a loop or Y strainer . also are the feed and return loops reversed on the manifold that can affect the balance of the system. they should be reversed to balance the flow. lastly i see a lot of very good advice , this site is the best.

I do have the Caleffi SEP4 low loss header which has a magnetized debris reservoir - it seems to do a good job off pulling off sediment/rust/debris.

I'm not sure what you mean by "are the feed and return loops reversed on the manifold"?

I completely agree - this site rocks and I'm learning a lot from you all!

Roobul

I found these specs for the Taco mixing valves, 5000 series (installed) and 5120 High Flow.
The math in previous comments by hot_rod indicates the 5000's CV of 2.3 will not allow for 7 GPM flow with the 0015e3 pump. If I replace the 5000 mv with the 5120 mv, increasing CV from 2.3 to 4.1 would lower the head pressure of the mv from 22' to 7', plus 5' for the loops - the 0015e3 pump can do 12' @ 7 GPM.
However, the 5120 specs show "Min temp differential btwn hot supply and mixed: 27*F" - does this mean that if we want 110* supply to the radiant manifold the input temp to the mv has to be >137* ?

hot_rod

For the valve to mix properly yes, you need pretty close to that temperature delta. 25-27 is common on most thermostatic valves 

what will happen without that required delta is the mixed outlet will vary a bit

There are other valves with tighter temperature requirements  The Caleffi 520 is 18 degree, but a low Cv again

There is a large body 520, 4 Cv but the piping would not match, it is. 45 degree valve pattern

Roobul

hot_rod said:

For the valve to mix properly yes, you need pretty close to that temperature delta. 25-27 is common on most thermostatic valves 

what will happen without that required delta is the mixed outlet will vary a bit

The mixing valve is currently set higher than the boiler's radiant target temp, so it acts as a high limit for radiant when the boiler comes off another hotter zone. I don't necessarily need it to mix accurately, just not allow >130* to go to the floors. Maybe I'd be better off with the electronic valve with sensors on the input and mix... Taco has the i100U3S for setpoint control (attached), but I don't see a comparable one from Caleffi.

hot_rod

Roobul said:

hot_rod said:

For the valve to mix properly yes, you need pretty close to that temperature delta. 25-27 is common on most thermostatic valves 

what will happen without that required delta is the mixed outlet will vary a bit

The mixing valve is currently set higher than the boiler's radiant target temp, so it acts as a high limit for radiant when the boiler comes off another hotter zone. I don't necessarily need it to mix accurately, just not allow >130* to go to the floors. Maybe I'd be better off with the electronic valve with sensors on the input and mix... Taco has the i100U3S for setpoint control (attached), but I don't see a comparable one from Caleffi.

That option gives you outdoor reset option also.

Roobul

hot_rod said:

That option gives you outdoor reset option also.

I saw that, but if the boiler already has an outdoor reset and adjusts the temp for radiant, do I need/want one on the mixing valve too?

hot_rod

Roobul said:

hot_rod said:

That option gives you outdoor reset option also.

I saw that, but if the boiler already has an outdoor reset and adjusts the temp for radiant, do I need/want one on the mixing valve too?

No you don’t need two ODR controls. It is an option with that valve, comes with the package.

Roobul

hot_rod said:

Some mixing valves have checks in the H and C port, and usually a small strainer to protect the check. The strainer is sometimes built into the sealing washer, so it cannot be left out, easily.

If it is an ASSE 1070, or a dual listed 1017/ 1070 mix valve it must have checks.
See if maybe that is causing a restriction. You don't need or want the checks or strainers for hydronic use.

I went to the supply house to see if they could put a 5003 manual mixing valve and an i100u3s iSeries electronic mixing valve on the counter so I could see if it's really a "drop-in replacement" or not. Well not only did they not have the iSeries, but never ordered or saw one before!

Anyway, I took the 5003 valve out and sure enough, it has fine metal screens built into the two rubber inlet gaskets, and check-valve balls. I managed to remove the screens and put it back together. With the 5-loop zone going, there is definitely more flow. With the pump on 3, I'm getting just over 0.6 GPM per loop, or ~3 GPM total. The Delta T came down to 10* F (rather than 30*) although it isn't as cold out today as previous tests - input manifold is 90*, return is 80*.

However, when I drop the pump speed to 2, the GPM drops to 0.4/loop or 2 GPM total. When I set it to 1, I get 0.2/loop or 1 GPM. So I'm guessing the system curve looks something like this red line, which indicates the head is around 17 feet (based on the intersection on the speed 3 pump curve).

The expected 5 feet head isn't holding up, so even without the screens the mixing valve seems to be adding about 12 feet. I guess I'll take the valve out again and see if I can get the check valves out... maybe that will reduce the head enough (i.e. down to 5 feet ) to get the pump working satisfactorily on speed 2 (10 feet total) for lower power consumption.

Roobul

Roobul said:

I guess I'll take the valve out again and see if I can get the check valves out... maybe that will reduce the head enough (i.e. down to 5 feet ) to get the pump working satisfactorily on speed 2 (10 feet total) for lower power consumption. 

I removed the check valves from the mixing valve and the GPM increased from 0.6 to 0.8 per loop with 5 loops open. With all 11 open I get 0.4 GPM per loop  (or ~4.5 GPM total). These are with pump speed at 3. When I drop pump speed to 2 (constant 10 ft head), I get ~0.4 GPM per loop x 5 = 2 GPM total. So removing the check valves reduced the head pressure a little bit but not much. 

hot_rod

What is the gpm per loop that you are looking for? .75 is about the high side for 1/2” loops. Ideally you will cover the load with .5-.6 gpm. Then the pressure drop is reasonable
.
Without knowing the desired flow rate, it seems like speed 3 is giving you about the most you would expect. I’d guess 40- 50 W of power consumption?
Do you consider that excessive for moving the amount of btus to cover the load?

Roobul

Without having a good heat loss analysis to begin with, we were aiming for 0.65 GPM per loop, so worst case I'd need 7.1 GPM total. While I'm still not getting that, it looks like I am getting 0.6 GPM per loop with up to 8 loops open at once, which will suffice for most days of the season, with the pump on 3.

On 3, the pump doesn't adjust its speed as loops open and close; it just goes full speed all the time. Max power consumption on this 0015e3 is 44W, which is very acceptable, but it's using 44W even when only one loop is open. If the system head was 10' the pump could be set to 2 and would use less power when < 8 loops are open. I suppose the extra watts cost a lot less than a new valve, so the ROI could be many years. Removing the screens and checks seems to have resolved the problem well enough, as I do see warmer floors at the ends of the loops and the delta T is down between 10*-20*F.

hot_rod

Are you planning on adding zone actuators in the manifold? If not there is no reason or means for the pump to modulate.

If you do add actuators a true delta p mode would be best. Working up to the max flow you need 

Roobul

hot_rod said:

Are you planning on adding zone actuators in the manifold? If not there is no reason or means for the pump to modulate.
If you do add actuators a true delta p mode would be best. Working up to the max flow you need 

Yes, there are zone actuators on each loop. Small room thermostats open one actuator, medium room thermostats open two actuators, and the large living/dining/kitchen area's thermostat opens 5 actuators. Multiple zones (and therefore loops) can be calling at the same time, so I can have anywhere from 1 to 11 loops open at once across the 6 zones. So the delta P settings (speed low or med) would be ideal, but on speed med (10 feet) it's not giving me as much flow as speed high (full speed). Based on flow rates I see at the manifold indicators, the red line drawn on the performance graph above (2/18) approximates the system curve, indicating 17 feet head with 5 or 6 loops open.

Another improvement came from changing the differential setting on the Azel thermostat from 1* to 2*. At 1* (default) it call for heat at 0.5* below set point, and turns off at 0.5* above set point, eg. at 70, on @ 69.5 and off at 70.5 - I changed the diff to 2*, so on at 69* and off at 71*, which allows the floor time to heat more evenly and cycles the boiler less.

HomerJSmith

I'm old and I'm running out of time, so reading all these posts and figuring out what every one is saying is reducing the time I can spend on more pleasurable pursuits. However...
I would like to see a flir pic of the floor loops when all the hot loops are shut off at the manifold and the cold loops are fully open. I think that would be interesting. Flow is the conveyor belt that moves heat energy from one point to another point. There is obvious lack of flow in the cold loops and these posts are trying to figure out why.
Looking at your photo of your manifolds, I would like to see which loops are hot and which are cold. perhaps you could mark them on your photo of the manifolds. H & C

Roobul

HomerJSmith said:

I'm old and I'm running out of time...

I appreciate you making time for this in your golden years! There are not hot and cold loops per se', it's a matter of the loops starting off hot but becoming cold by the end before it returns to the boiler. I've attached a FLIR pic of the same room but facing from the left 90* (as compared to the earlier pic). Here you can see the beginning of the loop that appeared cold in the other pic; you see that it starts off hot and gets cold as it goes across the floor. Then the next loop starts hot (by the chair) and it gets cold at the far side of the room. So it seems that for each loop the beginning section of the floor was absorbing all the heat before the water reached the latter section.

Removing the screens and check valves from the mixing valve increased the flow, so more heat is transferred to the whole floor as the "conveyor belt" is moving faster. Delta T dropped from 20*-30* to 10*-20*. The change to the thermostat range (2* btwn on/off, rather than 1*) lets the conveyor run longer as well, which also helped. Even tho the room gets slightly colder--then slightly warmer--than before, I don't really notice that wider temp range, but the sections of the floor that were colder are warmer now.

While the flow is better, the mixing valve is still restrictive and the pump has to run on full speed to keep up when multiple loops are open. While it's better now than before, putting in a mixing valve with a higher CV rating would likely allow the pump to run in delta P mode, saving some electricity, but even in full speed mode (3) it only uses 44 watts, so the electric savings would take quite a few years to make up for the cost of installing a new high-flow mixing valve.

HomerJSmith

So, you are saying that the flir pic is one long loop and not multiple loop in that room? If that is true, then you are running out of heat energy before you get to the end of the circuit. That is normal as the heat energy moves out of the water. It is hotter at the beginning of the circuit and colder as the water exits the circuit, the heat energy moving into the environment. The first flir pic shows a different scenario. A radical change in temperature between two loops which led me to believe that the pic showed two different circuits. One doesn't see that radical change in a single circuit (that never happens). The temperature would peter out like in your second flir pic.
If you second flir pic is correct, two things can cause that: insufficient flow and or low entering water temperature. That's it. If it is the flow as indicated by the flow indicators on the manifold, increase the flow to 1gpm. If you can't increase the flow look for the restriction. That would be the pump, mixing valve, or manifold-pex pressure losses.
The pump should create enough head pressure to overcome the sys pressure losses at the desired gpm. If not a bigger pump or a reduction of the circuit restrictions are in order.
The mixing valve regulates the output temp of the valve based the knob positioning. The range of the valve positioning has a max and minimum range. You can remove the knob screw, pulling the knob back a little and rotate it to the full travel range. That may increase the output temp to the manifold.
Sys pressure losses can severely affect flow. One of course is the mixing valve.
So increase the flow or temp.

Roobul

Thank you for your suggestions.
There are two loops in that room. They are on the same zone, so they always open and close together. In the 2nd pic, the first loop starts at the bottom of the pic and goes to the middle of the room. The second loop starts there in the middle and goes to the far end of the room. The first pic shows the same room, looking parallel to the pex, where the first loop ends and the second loop begins. Yes, the water temp peters out by the time it reaches the end of each respective loop. The increased flow has helped. A bigger pump like a 26-99 would cure it, at the expense of triple the power consumption. A higher flow mixing valve would also result in more flow. The mod/con boiler typically runs at <120* for the radiant zones, and the mixing valve is just a safety in case the boiler is coming off the DHW or air handler zones at 160*. I could raise the boiler temp for the radiant zone, but don't want to lose the efficiency of condensing....

HomerJSmith

So, you have two loops in that space that operate on one thermostat device and open and close together.

You say you have Bluefin manifolds. Your pic below:
Your pic of your installation.
Notice the difference between the two pics? The top pic shows the hot supply water going into the flow indicators and the cold return coming from the actuators/stops. Your setup show the hot water supply going into the stops and the return coming from the flow indicators. Does that make a difference? I don't see any thermo actuators or wiring to them in your sys photo. A closer shot might reveal them. Is all 11 loops controlled by one thermosatic device? I'm missing something here.

Roobul

After that installation pic was taken the plumber swapped the flow gauges and actuators, so the actuators are on the return. So it's the Bluefin pic but with the supply manifold above the return manifold.

HomerJSmith

Thanks, good to know. Ok, I think I'm getting it. Your first flir pic shows a hot loop on the right and the second loop on the left that is much colder. You notice the temp difference moving from the hot loop on the right to the cold loop on the left. Got it. Your second flir pic show this looking from the left toward the right. Got it. Here's your solution. Take the cold loop on your first flir pic, the left loop, and switch the pex connections on each manifold. Move the return pex to the supply manifold and the supply pex to the return manifold. This will eliminate the cold loop next to the hot loop in your first flir pic. This will put the colder returns next to the room walls where people don't normally walk. The layout of your serpentine loops is not the way I would have done it. I would have done the layout at 90 degrees to the current layout with the hottest loops at the exterior walls where the windows are. But whatda I know.
I'm assuming that the flow indicators for both loops are the same, GPM.

Roobul

Yes, you got it. I did consider reversing the flow of the loop on the left, so both loops start in the middle of the room and cool off towards the perimeter. Two things gave me pause, 1) the floor would still be uneven, and 2) the left side is adjacent to the foyer so the floor would be cool where you first enter the room. Now that I have better flow (from removing the screens and check valves from the mixing valve) these concerns are reduced, and it may be better to have the most heat in the center of the room. I agree, the serpentine perpendicular to the windows is not optimal, but too late now. If I could do it again, I'd have them use a Spiral pattern so the supply-side and return-side of each loop is interleaved.
Yes, the GPM is balanced across the loops with minor tweaking of the flow meters.

HomerJSmith

You have two choices--1) increase the flow 2) increase the supply water temperature.