How to not burn your engineered floor - above floor panels

WillC

Hi,

The flooring I want to install says max temp is 85F with hydronic system. Distributor I am working with, wants to install mixing valves which have a minimum setting of 85F. Thats the only type of valves he carries within that range, he mostly do hangars concrete slab installation.
Planning to use a Nest thermostat and boiler with ODR. Will that damage the floor? Is there another way to control the water temperature? Should I shop around to find a mixing valve with a lower setting?

Thanks

TAG

They all say 85 .... with ODR you don't need the nest. It's on its own

kcopp

People often confuse floor temperature and water temperature.
The flooring companies all say max 85F floor temp.
Depending on the design of the radiant system you could very well have 140F water temp and a max floor temp of 85F.
How is the tubing going into the floor?
Staple up? On top of the floor?

WillC

Thanks for the explanation guys, I got both temperatures mixed up.

I want the Nest for being able to control the temp via my cellphone.

Tubing is going above the floor in some floor panels like the Roth ones.
So without a floor sensor, there is no way to know if I exceed the 85F?

hot_rod

That is a pretty benign number, 85F surface. Wood floors in a sunny south facing room can and do get well above 85 occasionally.
Certainly you can program the boiler or mixing device to limit SWT, or add a floor sensor if it really concerns you.

PC7060

WillC said:

I want the Nest for being able to control the temp via my cellphone. 

I’ve tried both the Nest and the Honeywell 9000 series thermostat and found the Honeywell to much better option for web enabled control.  The Nest is pricey and tries to do too much.  It’s predictive software is better for hot air systems and I’ve found it tries to over compensate for normal behaviors such as ODR in hydronic systems. 

WillC

hot_rod said:

That is a pretty benign number, 85F surface. Wood floors in a sunny south facing room can and do get well above 85 occasionally.
Certainly you can program the boiler or mixing device to limit SWT, or add a floor sensor if it really concerns you.

Thanks I see your point, but with the sun it will be a couple of hours I think, maybe the 85F limit is more for a long term application.

Another question, I know you are not supposed to run tubing underneath a pantry closet, island, cabinet because you will spoil the food and also the heat wont be distributed well.

If my bed or my couch doesn't have feet to be isolated from the floor, can I "trap" some heat and exceed the flooring limit and damage it? House is in Manitoba, new built and well insulated but we have very cold winters -22F and below, I expect the heat to stay on for multiple hours.

Am I overthinking this?

hot_rod

Actually 82 surface is about all a bare foot can handle comfortably. Above that you feet may become sweaty and uncomfortable. healthyheating.com has some excellent reading and studies on radiant panel surface temperatures. 82 surface temperature in a room at 70 ambient would get you about 24 btu/ sq. ft output.
85 is a number the wood people seem to agree on, not really based on radiant floor comfort, but a comfort zone number for the wood.

pecmsg

WillC said:

Thanks for the explanation guys, I got both temperatures mixed up.

I want the Nest for being able to control the temp via my cellphone.

Tubing is going above the floor in some floor panels like the Roth ones.
So without a floor sensor, there is no way to know if I exceed the 85F?

In floor radiant is very slow reacting. The last thing you want is to constantly changer the temperature. Set it and forget it, let the outdoor reset control it.

Jamie Hall

To add to @pecmsg 's comment. You will need to disable all the "smart" and "learning" features of the Nest. Otherwise it will constantly fight with the floor and the boiler. Comfort will be poor, fuel usage will be out of sight. Radiant floor heat, depending on the floor, takes anywhere from 6 to 12 hours to respond to even a small space temperature change, and may take days to respond to a large -- 5 to 10 degree -- change.

If you feel a need to change your space temperature at shorter intervals, you need a heating type, in addition to the radiant floor, which can respond quickly. Baseboards, panel radiators, etc. They would need a higher temperature water from the boiler, and their own circulation system. They could be controlled by the Nest, with some tweaking.

WillC

Thanks for the replies, sorry for my delayed reply.

The house will be a "smart house", the idea to be able to have the heating system controlled by app sounds exciting even if I am not planning to consistently adjust it and will leave the Nest functions off.

I have played with LoopCAD (first time using this) and created the house.

Some rooms are hovering around 85F and one is above 85F. These temps are for the average coldest case scenario? I have -27.4F in the outdoor design location(location based) and rooms temps at 70F.
I'm exceeding 82F suggested by hot_rod.

So any outdoor temps colder than that or increase in indoor temps and I am going above 85F on all zones and 1 zone at 90F.

What can be done to reduce these floor temperature? Have I done a data entering mistake with this LoopCAD?

I have attached the second floor files.

Jamie Hall

The required floor temperature in a radiant heating system is governed entirely by the space heat loss. The rest of the design process is in figuring out how to get the floor up to that temperature.

So... yeah. Even in a very well insulated house at -27 outside (where? Alaska?) the floors are going to have to be that warm, or you will have to go to additional heat, such as panel radiators -- which is probably what I would do. A floor at 85 is pretty toasty underfoot, at least for my taste (the cats would be very happy, though...).

Zman

If you boiler has ODR, why are you considering mixing? The thermostatic mixing valves that most people are installing have no place in a hydronic system. They have CV values that are to low and often interfere with ODR.

The flooring companies have been playing this CYA game for years. The only time I have seen a floor damaged has been when either the installed flooring had high moisture content or the knucklehead installer cranked the water temp to 180. If you design a system with a design day water temp of <130, you will be fine.

WillC

I think I need to review again the design in LoopCAD, I started using ASHRAE and then switched to CSA this morning, and that kick out of the insulation data I had for my walls and windows. The strange thing is the temperatures in the above screenshot I posted did not change at all now that I have just changed my walls from R12 (default value) to R25 and attic from R30 (default value) to R50. I thought it would change...

@Jamie Hall, thanks for the info, the house is in Manitoba, Canada.

@Zman, I went that route because I was worried about heating too much my engineered floors and because I cant have a floor sensor with the Nest Thermostat, I wanted to control the temps going out of the mixing valve and set it to max 85F - I realized that this is not how you are suppose to do it. So I can remove all the mixing valve out of my project and let the ODR take control?

LoopCAD has the water temp at 127F, does that mean the water entering the rooms are at 127F, minus what is lost from basement to second floor and what LoopCAd is showing is the average floor temperature?

Zman

It is a condensing boiler? Are there zone tied to it that require higher temps?
I condensing boiler with ODR can limit the temps and would eliminate the need for a mixing valve.

hot_rod

There is usually a fudge factor in those design programs. So if you are within a few- 5 degrees I would not be too concerned. You are corrects in that the load number is at a design day. You can look up data for your location, going back 20- 30 years and see how often you are at that condition.
So maybe in a few areas for a few days of week you end up with a bit warmer floor surface, i doubt any damage will occur to the flooring.
SWT supply water temperature is what the boiler needs to supply that zone, it should also show surface temperature. Keep in mind floor coverings have a lot to do with the surface temperature, throw rugs, area carpets all have an affection that number and the floor output.

Option B is to add a few panel radiators in those high load areas to supplement.

Here is an example of some BIN data from the ASHRAE weather database

Jamie Hall

WillC said:

I think I need to review again the design in LoopCAD, I started using ASHRAE and then switched to CSA this morning, and that kick out of the insulation data I had for my walls and windows. The strange thing is the temperatures in the above screenshot I posted did not change at all now that I have just changed my walls from R12 (default value) to R25 and attic from R30 (default value) to R50. I thought it would change...

@Jamie Hall, thanks for the info, the house is in Manitoba, Canada.

@Zman, I went that route because I was worried about heating too much my engineered floors and because I cant have a floor sensor with the Nest Thermostat, I wanted to control the temps going out of the mixing valve and set it to max 85F - I realized that this is not how you are suppose to do it. So I can remove all the mixing valve out of my project and let the ODR take control?

LoopCAD has the water temp at 127F, does that mean the water entering the rooms are at 127F, minus what is lost from basement to second floor and what LoopCAd is showing is the average floor temperature?

There should have been a very slight decrease in predicted floor temperature with the insulation change -- but quite possibly not that much.

I am concerned about your plans for controlling the system. Radiant floors have, characteristically, very long lags -- even a few degrees change in space temperature can take a day or two. For this reason it is ill-advised -- in fact, almost impossible -- to control a radiant floor system with a space sensing thermostat, although they can and sometimes are used to trim the system for changed conditions. By far the best (and most efficient and economical) control is to use outdoor reset to vary the output of a modulating boiler to the demand. This does take a little time to get right -- tweaking the relationship of boiler output to outdoor temperature -- but once it's properly set, it works very well. In some installations -- say a wood floor with plates -- the response time to a change in demand may be as little as a few hours, but even then such things as daily setbacks are likely to be disappointing at best. If you d insist on using the Nest -- or any "learning" or "smart" thermostat -- disable all the learning functions and setbacks.

The water temperature going to the floor usually will be considerably higher than 85; the objective is to keep the floor temperature at that on the design day (it will be lower on warmer days, of course). As mentioned above, a modulating boiler with outdoor reset is the best approach to that, Without the modulating boiler, it will be necessary for the boiler to cycle on and off to maintain the desired water temperature, and there are several control strategies for that -- mostly involving at least one aquastat and a floor sensor, and often a controlled mixing valve.

Rich_49

WillC said:

I think I need to review again the design in LoopCAD, I started using ASHRAE and then switched to CSA this morning, and that kick out of the insulation data I had for my walls and windows. The strange thing is the temperatures in the above screenshot I posted did not change at all now that I have just changed my walls from R12 (default value) to R25 and attic from R30 (default value) to R50. I thought it would change...

@Jamie Hall, thanks for the info, the house is in Manitoba, Canada.

@Zman, I went that route because I was worried about heating too much my engineered floors and because I cant have a floor sensor with the Nest Thermostat, I wanted to control the temps going out of the mixing valve and set it to max 85F - I realized that this is not how you are suppose to do it. So I can remove all the mixing valve out of my project and let the ODR take control?

LoopCAD has the water temp at 127F, does that mean the water entering the rooms are at 127F, minus what is lost from basement to second floor and what LoopCAd is showing is the average floor temperature?

R Values above R15 begin to have very little effect on BTUh . Your infiltration rates become the biggest factor at that point .

As far as finished floor surface temps are concerned , hardwood sales folks and installers love to have radiant to blame for issues . As Bob ( Hot Rod ) stated , those temps have less to do with actual damage to a wood floor as they do with physiology of the human body and comfort . these concerning surface temps you are inquiring about MAY happen about 2% of the heating season , at night for a couple hours over the course of Dec , Jan , Feb . Short excursions above 85*F surface temp will do no harm to the floors , especially engineered stuff that is much more stable .

WillC

Hi guys, I worked a bit more on the design and spent some time reading and understanding your answers.

My boiler in LoopCAD was set by default at 127F, I was able to reduce the SWT to 118F, matched the "required" floor temperature with the "actual" floor temperature and I am averaging 82.3F on all zones with the max temp in the master bedroom at 84.5F, pretty happy with that, on the high side but no burned feet and no need for additional heat!

@Zman: The boiler is a condensing one. HTP Elite Ultra 199 WCN. The master bedroom is the room with the highest require temps of the entire house (probably because of the double sliding doors)

@Jamie Hall: Thanks a lot for the explanation, if I go with the Nest it is to have all the HVAC electric/lights functions of the house under one same app. The Nest smart features will be off and it will be used as a normal air thermostat. I understand it will be more expensive to go that route but we like the idea to have the heating controlled by one app even if we don't touch the temperature. I will have to call to see if the boiler is a modulating one or not, cant find this in the online brochure.

@Rich_49: Thanks, looks like insulation has no effect at that point. You are right, all these limitations on every flooring I could find made me worried for nothing. Humidity seems to be the biggest issue after reading everybody experience.

I have another issue on the second floor, I have attached a screenshot of LoopCAD.

SWT 118F, rooms temperature at 70F, all floors have 1/2 PEX at 6" spacing, manifold providing 118F. The master bedroom is asking and getting surface floor of 84.5F, the ensuite is asking for 74.8F but is getting 83.1F. Both room are on 2 different zones with their own respective thermostat.

If I understand properly, this overheating in the ensuite is due to the manifold being at 118F and the circuit length too long.

How can I reduce the temperature, should I first add balancing valves for the ensuite circuits? How much can I drop the flow and the temperature?

Or maybe should I use a 9" spacing for the bathroom?

thanks