Trying to Make Temp...

[maple1]

Do you monitor humidity levels with a humidity monitor? Preferably more than one? Is there a ventilation system in the house?

Hearing the need for a dehumidifier in the winter is a bit surprising. I vent our drier indoors, we don't have any vent fans in the bathroom or kitchen that vent outside, I keep our winters wood in the basement, and we use a clothes rack in the bathroom for drying clothes once in a while. Our Venmar can keep the humidity levels good all winter just by running intermittently, quite infrequently. House is typical 20 year old construction. It is on a windy hilltop though. Usually people find the need to humidify in the winter, and not dehumidify. Is there an open sump or do you get water seepage into the basement?

(Guess we're getting a bit off the topic....)

 

[CaptainK]

Do you monitor humidity levels with a humidity monitor? Preferably more than one? Is there a ventilation system in the house?

Hearing the need for a dehumidifier in the winter is a bit surprising. I vent our drier indoors, we don't have any vent fans in the bathroom or kitchen that vent outside, I keep our winters wood in the basement, and we use a clothes rack in the bathroom for drying clothes once in a while. Our Venmar can keep the humidity levels good all winter just by running intermittently, quite infrequently. House is typical 20 year old construction. It is on a windy hilltop though. Usually people find the need to humidify in the winter, and not dehumidify. Is there an open sump or do you get water seepage into the basement?

(Guess we're getting a bit off the topic....)

In order...

No, just the dehumidifier in the crawlspace.

No air exchanger in the house. (have considered but not yet acted) there where other projects that needed more attention (new roof, encapsulate crawlspace, and new heating system)

1940's home on ledge, with some water seepage into the basement if it rains hard for extended periods. Basement has gutter system around edge of foundation with a gravity drain to route water back outside. Mostly happens in spring.

Dehumidifier runs all year, less in the winter but still all year. Was thinking I would add gutters to the roof to keep rainwater away from the foundation then if need be encapsulate the rest of basement before I try the air exchanger route...

Yes a bit off-topic but relevant to heating somehow I'm sure.

 

[maple1]

Ah, crawlspace, OK - those can be very different animals.

I would be quite surprised then to see any hardwood damage from the heated floors, with that much interior humidity in the winter.

But they're still not my floors though - so good luck with it & keep on with the updates.

 

[Karl_northwind]

What is your insulation under the floor, staple up with heavy plates, no plates, light plates? and what is your return temp from the floor?, not just supply temp?

 

[redmaple172]

I had staple up in my old house, with tile above subfloor. I think I ran 120 degrees on mixing valve with a three speed pump (lowest setting worked best-maybe allowed heat to transfer at a better rate?). Cast iron radiators removed in those rooms with floor heat so the floor was the heat source. I used regular (honeywell) tstat. My house now I used Tekmar tstat that has floor and air sensor - this allows great adjustability. Floor is pex in 1" cement (sand mix) with tile on top (slate in kitchen). I also have forced air heat in entire house. I used Taco mixing block for floors. Temperatures range from 95 to 125 (all adjustable settings) and have three speed pumps. Three zones and each pump is set at a different speed. It's took a winter to get everything adjusted correctly. I still can't get kitchen slate floor to always feel warm without having the room get to hot. The tstats I have might help you - you can set a minimum floor temp (I do 70 in kitchen, much higher in bathrooms). Just look for tstat with floor sensor.

 

[CaptainK]

What is your insulation under the floor, staple up with heavy plates, no plates, light plates? and what is your return temp from the floor?, not just supply temp?

Hope this covers it... we have not have cold weather for the last few days, this is from memory. I have been looking at it enough that I'm confident in the numbers.

Light plates, (Uponor Joist Trak)
Supply from mixing valve at Boiler 135
Supply at Header 120
Return at Header 110
Return at Boiler 110

Pardon the delay in my response, I work strange hours...

 

[CaptainK]

I had staple up in my old house, with tile above subfloor. I think I ran 120 degrees on mixing valve with a three speed pump (lowest setting worked best-maybe allowed heat to transfer at a better rate?). Cast iron radiators removed in those rooms with floor heat so the floor was the heat source. I used regular (honeywell) tstat. My house now I used Tekmar tstat that has floor and air sensor - this allows great adjustability. Floor is pex in 1" cement (sand mix) with tile on top (slate in kitchen). I also have forced air heat in entire house. I used Taco mixing block for floors. Temperatures range from 95 to 125 (all adjustable settings) and have three speed pumps. Three zones and each pump is set at a different speed. It's took a winter to get everything adjusted correctly. I still can't get kitchen slate floor to always feel warm without having the room get to hot. The tstats I have might help you - you can set a minimum floor temp (I do 70 in kitchen, much higher in bathrooms). Just look for tstat with floor sensor.

Will look into the floor sensors, where do you mount/install them? Just stick it to the floor? I can see how keeping the floor at temp would help regulate the room temp... It looks like the model 521 is the way to go.

 

[lotawood]

I use a tekmar 528 on a concrete floor in a shop.

I just tapped it to the floor in between the water loops. Then I covered it with insulation. It is under a toolbox so it is not in the way.

Your might have to come up with an eye appealing spot. Wood floors, should be easy to pull up a plank and router a groove underneath.

The tekmar I have works so well I can ignore it all winter.

 

[redmaple172]

I embedded mine the grout. Right under the hardwood I think is recommended, or in tile dig out some grout. I would think you could hide it near baseboard or door casing.

 

[woodsmaster]

Id just drill a hole with a masonry bit and hammer drill. being carefull not to hit a water line stick the sensor in and cover with woodputty if you so desire. I think id do it along an interior wall to keep it away from the perimeter a little.

 

[Willman]

Heres a pic of my bathroom floor tubing. Note straight piece which I curved up wall to receive the floor sensor. Foam product is bekotec from Shluter which requires a mud setting bed for tile or maybe floating wood floor.

 

[Bob Rohr]

floor temperature around 80-82F is a good target. 85F starts to feel a bit too warm to bare feet, and your feet may start to sweat. It's all is based on average skin temperature and this link shows how skin temperature varies based on ambient. Plenty of other good human comfort heating advice at this site.

(broken link removed to http://www.healthyheating.com/Definitions/facts_about_skin.htm#.VHqIyIv6SS0)

The challenge will be getting enough surface area to 80F or so. Throw rugs, especially with backing material, or no slip pads, really dampen the output as you have discovered by the temperature below them

Really you need to determine what the heat load is for every room served by the radiant, the supply temperature required is based on the load, but also the r value of the flooring. Two layers of 3/4 hard and soft wood is an R-1.8.

IF you need 20 BTU/ square foot output to cover the load, you would need about 110F supply at the tubing, run a tight delta T so you still have good output at the end of the loop.

Remember any furniture that covers the floor, couches, over-stuff chairs, etc lessen the radiant panel square footage available to cover the load. Kitchens can be hard to heat due to all the cabinetry that covers the floor, sometimes there is not enough open floor area to cover the load.

Also critical is the tube spacing as the floor is warmest over the tubes and decreases between the tube spacing, so maintaining a constant floor temperature requires no more than 8" on center spacing on dry staple up systems. This is why concrete slabs spread that heat energy better.

If you have a point and shoot temperature gun measure the temperature gradient across the entire floor, see how much it varies between the plates.

There comes a point on high load rooms and floor covering restrictions, where the floor output alone may not be enough, keeping in mind the floor surface temperature max. of 80- 82F.

 

[CaptainK]

Update: With a few cold days now behind us and a tweak to the temp here is what I have.

All temps are after things have stabilized. Supply temp may drop to 110 not sure why this is, I thought the mixing valve worked like a pressure regulator, constantly changing the mix to yield the desired temp. But seems to work more like a faucet fixture, the mix ratio is fixed and varies on the input and the output... strange. After things are up to temp everything statblizes nicely. Now that we have some warmer days head Ill see how bad we overshoot...

Supply from mixing valve at boiler 140-145
Temp at Header Supply 125
Temp at Header Return 110
Temp at boiler Return 100-110

Floor temps after running stable and before shutdown, 76-81 Depending on room & location. (about 90 under any area rugs) Have not seen the thermostat drop below 69 (set at 70) warmest temp seen is 73 (solar gains) Even after hitting 73 and the temp dropping outside lowest seen was 69 That's not bad!

 

[Bob Rohr]

Supply from mixing valve at boiler 140-145
Temp at Header Supply 125
Temp at Header Return 110
Temp at boiler Return 100-110
Floor temps after running stable and before shutdown, 76-81 Depending on room & location. (about 90 under any area rugs) Have not seen the thermostat drop below 69 (set at 70) warmest temp seen is 73 (solar gains) Even after hitting 73 and the temp dropping outside lowest seen was 69 That's not bad!

Update: With a few cold days now behind us and a tweak to the temp here is what I have.

All temps are after things have stabilized. Supply temp may drop to 110 not sure why this is, I thought the mixing valve worked like a pressure regulator, constantly changing the mix to yield the desired temp. But seems to work more like a faucet fixture, the mix ratio is fixed and varies on the input and the output... strange. After things are up to temp everything statblizes nicely. Now that we have some warmer days head Ill see how bad we overshoot...

Supply from mixing valve at boiler 140-145
Temp at Header Supply 125
Temp at Header Return 110
Temp at boiler Return 100-110

Floor temps after running stable and before shutdown, 76-81 Depending on room & location. (about 90 under any area rugs) Have not seen the thermostat drop below 69 (set at 70) warmest temp seen is 73 (solar gains) Even after hitting 73 and the temp dropping outside lowest seen was 69 That's not bad!

Curious why the mix valve outlet is 145, but the supply at the header is 125? Why the 20°drop in temperature?

 

[CaptainK]

Curious why the mix valve outlet is 145, but the supply at the header is 125? Why the 20°drop in temperature?

Good question, I don't have an answer for you, from the mixing valve it goes to the zone pump then out to 1" pex, about a 20' run to the header, could be an inaccurate thermometer on the header... I would not think that pex would loose that much over that distance. You can see the header pic attached.