Staple Up radiant not warming room

Kkane97

I recently converted one zone of my boiler system, to radiant staple up flooring. Mixing valve set at 140° My Google nest thermostats show that is ran 20.5 hours in the last 24 hours with average outside temperatures of 40°. Room was just re-insulated and refinished with r21 insulation r30 ceiling r21 basement ceiling.  The total radiant loop is 280ft long 1/2 pex . Taco 007e circ pump I'm not sure how many gph it flows at in my system. Im concerned that in the winter months of colder temps I may have  problem maintaining a temperature in the room and looking for solutions or options ideas . 

Jamie Hall

Any idea what the actual heat loss of that room is? It would help to know. The maximum you can get out of a radiant floor is somewhere around 25 BTUh per square foot.

Also you input temperature is pretty high for radiant. You might be better served with a lower temperature, but more flow. What is the delta T between the input and the return?

Kkane97

Jamie Hall said:

Any idea what the actual heat loss of that room is? It would help to know. The maximum you can get out of a radiant floor is somewhere around 25 BTUh per square foot. Also you input temperature is pretty high for radiant. You might be better served with a lower temperature, but more flow. What is the delta T between the input and the return?

I have turned up the  temperature seeing if it would decrease the pumps run time daily. What do I need to know as to calculate heat loss?  
Circulator running for about 30 minutes, Room temperature of 65 water and temperature of 142° and water return temperature of 125°  does that give me a delta t of 17°? If I understand it correct delta T is heat loss across the zone

Jamie Hall

To calculate heat loss you need the wall and floor and ceiling areas, and their construction and insulation. Then it's not hard. There are some on-line calculators.

Determining delta T is simple. The simplest is an IR thermometer, and check the temperature of the supply and return pipes. You want to adjust the flow rate so that it is somewhere around 20 degrees F.

You also want to adjust the supply temperature so that the pump runs all the time -- which means the supply temperature will vary somewhat with how much heat your need.

Kkane97

Jamie Hall said:

To calculate heat loss you need the wall and floor and ceiling areas, and their construction and insulation. Then it's not hard. There are some on-line calculators. Determining delta T is simple. The simplest is an IR thermometer, and check the temperature of the supply and return pipes. You want to adjust the flow rate so that it is somewhere around 20 degrees F. You also want to adjust the supply temperature so that the pump runs all the time -- which means the supply temperature will vary somewhat with how much heat your need.

So as far as delta T as I commented above I'm right where I want to be as far as flow? I know the taco 007e pump is variable flow as far as head pressure, single story house there is 3 ft of head with 280 ft of PEX in my zone. 17 degrees was my difference in the return and inlet temperature 

This is what I came up with for heat loss, I have 2 layers of r 30 in my attic above the room and insulation on the basement ceiling below the staple up radiant there was no option to change the parameters besides insulation or no insulation

hot_rod

Did you use aluminum transfer plates? 8” on center tube spacing?
Bare tube staple up may not get the job done

Kkane97

I have the system set to 90 just trying to see how hot I can get the room to. 1/2 oxygen barrier pex 8" spacing between joists with 4" aluminum heat sink plates - 8" for the turn at the end of the room. 
Mixing valve outlet 135° 
Pump return inlet 122°
Taco pump is on normal mode my guess is about 4 gph according the the chart
It has been on all day and the room is 68° outside temps here are about 40°

I'm considering swapping the pump with the older taco 007 I have that is non ecm controlled

It just doesn't seem right I can't get it that warm still

I have two layers of r30 in my attic, good deal at a auction I figured It couldn't hurt for a little extra 

I recorded a video that maybe will help explain it better let me know if the link doesn't work

https://drive.google.com/file/d/17r80jTrOTsYIt6KPbgJoS2LACcTsSqvv/view?usp=drivesdk

bburd

What's the floor finish in this room?

Kkane97

bburd said:

What's the floor finish in this room?

Plank subfloor 1/2 OSB LifeProof lvp 6mil

GroundUp

17* X .7GPM = 5950 BTU so either your pump is not moving what it's supposed to be moving or your heat loss was incredibly inaccurate. How many cubic feet is this space?

Rich_49

Is this room an individual zone ? A proper heat loss will show the floor surface temp that should be adequate . If this is an isolated zone , turn the water temp on the mixing valve UP . Don't be alarmed by crybabies who do not understand that water temp may destroy your floors , when the correct or necessary surface temp is reached the zone will shut down as will flow and the surface temp can climb no higher . You have to do that work first though to determine if radiant was even feasible to begin with . Remember also , even though you used nice R values on your insulation , EVEN the very good windows and doors are terrible walls . Smaller rooms very often have higher loads than rooms that are larger .

It looks like there is an airspace above the insulation also , is this the case ? If so , push the insulation up tight to the floor , conduction is where you will gain the most heat transfer in this type of install

HomerJSmith

Shoot the top of floor with your laser thermometer. I would look at the flow. No flow no heat. If that is the only zone operating and the boiler cycles off when there is a call for heat you may not have flow. The return temp might just be heat energy coming up from the boiler return pipe giving a false reading.

The ideal is a IR camera and a look see of the piping on the floor to see your heat signature. If there is only insulation and not drywall over the pex, just reach up and feel the pex at the supply and return as to heat.

Kkane97

GroundUp said:

17* X .7GPM = 5950 BTU so either your pump is not moving what it's supposed to be moving or your heat loss was incredibly inaccurate. How many cubic feet is this space?

The room is about 155 sq ft, where are you getting the numbers in your btu calc? 17° is delta T?

Kkane97

Rich_49 said:

Is this room an individual zone ? A proper heat loss will show the floor surface temp that should be adequate . If this is an isolated zone , turn the water temp on the mixing valve UP . Don't be alarmed by crybabies who do not understand that water temp may destroy your floors , when the correct or necessary surface temp is reached the zone will shut down as will flow and the surface temp can climb no higher . You have to do that work first though to determine if radiant was even feasible to begin with . Remember also , even though you used nice R values on your insulation , EVEN the very good windows and doors are terrible walls . Smaller rooms very often have higher loads than rooms that are larger . It looks like there is an airspace above the insulation also , is this the case ? If so , push the insulation up tight to the floor , conduction is where you will gain the most heat transfer in this type of install

The room is a individual zone , it also has the bathroom on it at the end of the loop.  I have a 2" air space between the r21 insulation on the floor and the tubes

Kkane97

HomerJSmith said:

Shoot the top of floor with your laser thermometer. I would look at the flow. No flow no heat. If that is the only zone operating and the boiler cycles off when there is a call for heat you may not have flow. The return temp might just be heat energy coming up from the boiler return pipe giving a false reading. The ideal is a IR camera and a look see of the piping on the floor to see your heat signature. If there is only insulation and not drywall over the pex, just reach up and feel the pex at the supply and return as to heat.

Providing my temp gun is accurate which it has seemed to be the top side of the floors are about 74° and the basement side are 81

kcopp

Where is the circulator in relation to the mix valve? I didnt see it in the video... it should be pulling out of the mix valve

Kkane97

kcopp said:

Where is the circulator in relation to the mix valve? I didnt see it in the video... it should be pulling out of the mix valve

This post is from when I changed everything over @hot_rod had some concerns of my pump location as I am pushing into the cold port of the valve, but water temperature has been very steady and maintained the temperature as I have set itis 

kcopp

IMO this is the issue. Not enough flow rate. You really need to pull out of the mix side valve

hot_rod

You need both flow and temperature differential to move heat energy

The grand old hydronic formula, simply stated as 500 (f) (delta t)

Kkane97

kcopp said:

IMO this is the issue. Not enough flow rate. You really need to pull out of the mix side valve

Is there a possibility as an issue with the circulator pump as far as how much flow it is using

Hot rod discussed this in the other post that I had when I set the system up, I am pulling out of the mixing port but I'm not pulling directly out of it. I'm pulling out of it through the loop, and before the return port of the mixing valve

hot_rod

What I can say with complete confidence is that thermostatic mixing valves work perfectly when you pump away from the mixed port😃
 You would need to calculate the pressure drop if the circuit in relationships to the pressure drop across the valve

That is a 3 cv valve, if you are flowing anything less than 3 gpm, you have very low pressure drop across the valve, but more pressure drop thru the loop. So flow will tend to  cross inside the valve instead if going to the circuit

Your observations seem to confirm this?

Kkane97

hot_rod said:

What I can say with complete confidence is that thermostatic mixing valves work perfectly when you pump away from the mixed port😃
 You would need to calculate the pressure drop if the circuit in relationships to the pressure drop across the valve

That is a 3 cv valve, if you are flowing anything less than 3 gpm, you have very low pressure drop across the valve, but more pressure drop thru the loop. So flow will tend to  cross inside the valve instead if going to the circuit

Your observations seem to confirm this?

I haven't looked into anything as far as determining the actual amount of flow. I am not sure how to do that. Would adding pressure gauges before and after The zone help confirm that ?

Kkane97

With the typical BTU output of staple of radiant flooring, would I typically be able to make the room actually reach 90°?

kcopp

Move the pump and see what happens. I have seen this time and again where people try to force water back into the mix vale and it fails each the time.

psb75

Why don't you do "a little plumbing" and put the floor-zone circulator in the right place? Move the floor circ. to the left (in the picture)-- installed on the "mixed" line "out" of the mixing valve--and have it "pumping away" (pump arrow pointing "up") from the mixing valve.

GroundUp

I asked for cubic footage, not square footage. An average 280ft loop of 1/2" pex will flow roughly .7-.8 GPM so I used .7 as the multiplier and your supplied 17 degree delta T which comes out to 5950 BTU. Therefore, either your heat loss calculation was way off or you're not getting enough flow through the loop. A 74* surface temp is only going to yield a 69-70* air temp under perfect conditions, so you need a higher supply water temp to raise that surface temp which will also raise the delta T and therefore emit more BTUs. The way your system is piped, especially with the check valve on the outlet of the circ, you're very likely forcing return water to the mixing valve. First turn the water temp up to 150ish and see how that goes, and if it's still unsuccessful, move the circ over to the mixed side of the mixing valve where it should be and eliminate that variable.

hot_rod

Kkane97 said:

With the typical BTU output of staple of radiant flooring, would I typically be able to make the room actually reach 90°?

A 90° floor would be very uncomfortable to walk on in bare feet. Somewhere around 82F is about as warm as we typically recommend for hard surface residential slab.
In a shop where occupants have work boots on, we can bump that a bit to get extra output.

Accurate pressure gauges across the circulator would allow you to determine actual gpm. Method 3 &4 are the most accurate.
Idronics 16 walks you through an example of calculating flow via the pump differential method.

Or but a Caleffi Quicksetter

Kkane97

Thank you for the information hotrod, since turning the temperature up on the floor I am steady with 76 on the top surface and yesterday with outside temps of 37° the system ran 6 hours total. Not exactly having a issue I didn't think it was working as good as it could  I will be changing the pump flow path around and will update when I do so 

kcopp

How did this work out?

Kkane97

I have not changed the flow path of the circulator pump location yet, it is working with no issues really. When I redid the room as far and the sheetrock, I realized that I never put the insulation back in the ceiling . That was the issue. I overlooked that as it has been under construction slowly for the last year. I have had no issue maintaining room temperature of 72° with an average thermostat heat call daily of 7.5 hours. It's been in the upper 30s around here the last few weeks. I am working on changing some of the system again and have made another post on adding a OWB to the system, and plan on reworking the circulator location while the system is drained.