I would like opinions of below floor and plate radiant systems vs. extended surface suspended tube radiant. I like the latter because of the omission of mixing requirements ...but does it provide heat comparable to a below floor and plate system if installed properly? If not ... can someone tell me how much of a difference there is and if there is any info of how to determine the amount of heat an extended surface suspended system can produce when supplied with a certain temp of water and flow rate etc.. Thank you, RH
Radiant floor heat - Below floor and plate vs. extended surface suspended tube
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aluminum transfer plates move heat by conduction. It is a much stronger transfer than convection which is what bare tube suspended below the floor gives you. Typically you can use much lower supply temperatures in transfer plate applications, maybe 20 degrees or more. Depending on the heat load of the space you may get down as low as 120F supply temperatures.
Transfer plates are usually a faster responding system and nicer temperature spread across the floor.
However if one were to do a suspended tube radiant I would suggest the UltraFin product. It does help with the thermal transfer from the tube to the space. The UF is nice if you want to add some radiant to an exisiting baseboard system for example. Nice for a bathroom or kitchen floor warming zone. It can run the same temperature as the baseboard.
I have installed a couple UF systems on outdoor reset and they will heat with as low as 140F supply in my somewhat mild climate. Works well with a condensing boiler when you go that low. The early version UF had a pop rivit assembly, slow and tedious. i see they now use a clip of sorts?
If you go with an underfloor system consider PAP tube. It may be a little more work to pull through but it doesn't squirm around as much leading to potential noise problems.
Plenty of isulation under those high temperature UF systems at least a 6" batt, and leave an air space.
With plates you can push the insulation right up to the plates. I have spray foamed a few transfer plate jobs also.
Pay attention to the rim insulation detail. It's a big heat loss area, especially with rim seal leaks
expanding foam is a great way to insulate rim joist areas.
hr
Transfer plates are usually a faster responding system and nicer temperature spread across the floor.
However if one were to do a suspended tube radiant I would suggest the UltraFin product. It does help with the thermal transfer from the tube to the space. The UF is nice if you want to add some radiant to an exisiting baseboard system for example. Nice for a bathroom or kitchen floor warming zone. It can run the same temperature as the baseboard.
I have installed a couple UF systems on outdoor reset and they will heat with as low as 140F supply in my somewhat mild climate. Works well with a condensing boiler when you go that low. The early version UF had a pop rivit assembly, slow and tedious. i see they now use a clip of sorts?
If you go with an underfloor system consider PAP tube. It may be a little more work to pull through but it doesn't squirm around as much leading to potential noise problems.
Plenty of isulation under those high temperature UF systems at least a 6" batt, and leave an air space.
With plates you can push the insulation right up to the plates. I have spray foamed a few transfer plate jobs also.
Pay attention to the rim insulation detail. It's a big heat loss area, especially with rim seal leaks
expanding foam is a great way to insulate rim joist areas.hr
Thank you for the response. The UF product was exactly the one I was wondering about. I am in Tennessee and the install would would be in an existing older house. So even with proper insullation .....are you indicating that I would only be able to use the UF product as a supplement to baseboard or radiant panel heating? Do you know of any resource to calculate the amount of heat you can get from the UF product given the temp and flow of the water through the tubing? Thank you, RH
RH
I did my mbedrm and walkin closet with Ultra Fin and PAP. Great system to keep your floors at the same level. Slight trade off against higher water temp. I followed their heat loss calculator. @ my design temp it keeps area 72* no problem. The first half of winter I ran it with 180 ish* water. Way too hot. Installed mix valve and now use 145* water. Still great comfort. Zone runs longer @ lower temp without causing too much extra boiler firing. I used 2 layers of poly iso foam board for insulation. Rim joists (8x8 beam) insulated and spray foamed and caulked also.Spendy but I own it. I ran it perpendicular to joists, I feel as if the heat distribution is more even. Labor intensive install though. My current load lowering project is infloor mud bed tile job in 2 bathrooms. Shooting for 100ish* water or thereabouts.
IMHO stratification strategy begins with the loads.
HR's statement to run with BB meant with same temp water not with BB in same room unless an extremely large heat loss..
I did my mbedrm and walkin closet with Ultra Fin and PAP. Great system to keep your floors at the same level. Slight trade off against higher water temp. I followed their heat loss calculator. @ my design temp it keeps area 72* no problem. The first half of winter I ran it with 180 ish* water. Way too hot. Installed mix valve and now use 145* water. Still great comfort. Zone runs longer @ lower temp without causing too much extra boiler firing. I used 2 layers of poly iso foam board for insulation. Rim joists (8x8 beam) insulated and spray foamed and caulked also.Spendy but I own it. I ran it perpendicular to joists, I feel as if the heat distribution is more even. Labor intensive install though. My current load lowering project is infloor mud bed tile job in 2 bathrooms. Shooting for 100ish* water or thereabouts.
IMHO stratification strategy begins with the loads.
HR's statement to run with BB meant with same temp water not with BB in same room unless an extremely large heat loss..
Hi Willman ....Thank you for the reply. One of the reasons I am considering the Ultrafin is to get rid of the mixing aspect. You indicate that you felt the need to mix and lower the temp on the water. Were you actually getting too much heat from the Ultrafin system? I also would like to avoid using baseboard along with the Ultrafin in the rooms that I would install it ....if I have either use mixing or also have baseboard in the rooms that I use the Ultrafin in it seems to me that I might as well just do under joist tube and plate radiant. That is unless I am missing something here. ... RH
The goal of a radiant install is floor temp. A generally accepted goal is 87* floor temp. This will provide a comfortable temp in room. Running UF on 180* water brought the room up to temp real quick and due to higher water temps tended to overshoot which resulted in warmer temps. The other side of the coin is boiler cycling.. I feel as the lower water temp results in less cycling and definitely doesn't overshoot. Thermostat stays on 72* no matter what. Economy of operation is the name of the game no matter which method of firing is used.
The only downside was -WAF. She noticed floor wasn't as toasty after the mixing valve was installed. Its no big deal to purchase or install one, check em out on Ebay. Another upside to radiant is no baseboards and the resultant air movement within room. Much cleaner also.
Your design temp in Tenn. shouldn't be that low. There is no reason the UF wouldn't work for whole house install. Go to ultra fin website for their calculator. call em up. Real helpful people.
Will do Willman .... your input is encouraging that UF will work as well as the under joist plate concept. I will be using an OWB with a heat exchanger and will probably put a loop of baseboard or maybe panel radiators in the upstairs of the house ...then put the UF system after that ....so maybe I would not need mixing after the heat loss from the exchanger as well as the radiators before the UF. What I wanted to find out is if the Ultrafin could provide enough radiant heat ...and your experience indicates that it can ....so I wil pursue the concept. The design temp in Tenessee where I am is 0. Thank you again ...RH
I received some input today that frowned on the Ultra-Fin product because of the higher temp it tends to run well with. The source said that he did not recoomend it because with that higher temp it can be noisier than regular pipe and plate systems that run at lower temps. Any input on this from those of you that have used the Ultra-Fin product? Thx again, RH
I have been using Onix from Watts Radiant for underfloor aplications for years with little change to the design temp vs. Pex with plates and it is much easier to install. Not only that there is no movement due to thermal expansion. NO ticking. Trust me I live with an onix staple up system and have installed tons of it for customers and never had a problem heating. Do a proper heat loss calc and you will be in great shape. You can download radiant works pro from wattsradiant.com
I forgot to say NEVER suspend pex underfloor unless you are willing to insulate perfectly and run 180 deg.F and like to hear your system move as you try to sleep. I speak from sad experiance.
Boilergeek ...I just looked at the Watts site ....am I correct that they just recommend a staple up installation ...with no plates at all? Also what about fittings for this product? It looks like it is a form of Pex Al Pex so does it use the same fittings as Pex Al Pex? Thx, RH
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