Green Build AB
Registered Users
New Member
Posts:14
 |
| 09/01/2009 3:12 PM |
|
| I live in Alberta, Canada. I am putting hydronic heating in my basement and want to heat my upstair bathrooms with the hydronic system as well. My heating contractor cannot give me a good answer about what to do with the pex. I was thinking about using the small tubes over the floor, but have been told I should run it under the floor between the joists. My concern with puting above the floor is the height issue, although I should be fine. Transition from the hardwood to the tile will be a little uneven. If I put it between the joists, I have to run the boiler warmer then cool it down for the basement. Any recommendations? |
|
|
|
|
|
|
James Eggert
Registered Users
Veteran Member
Posts:1059
|
| 09/02/2009 5:45 AM |
|
Any recommendations?????????
Maybe you need a contractor with more experience with radiant?
You can run the tubing under the floor, just increase the number of loops to increase the available heat transfer for the same supply temp.
Keep in mind though, the heat transfer thru the layers of flooring, sheathing, cement board, etc, does impact output, so plan accordingly. |
|
Take Care
Jim
Design/Build/Consulting
"Not So Big" Design Proponent |
|
|
Green Build AB
Registered Users
New Member
Posts:14
|
| 09/02/2009 8:46 AM |
|
| Thanks. The design guys do not want me to increase the length of pipe as they claim that the loops should all be about the same length to properly balance the system. I am certainly in an area where the expertise for radiant is lacking. There much more information on this site than I could ever hope to get from my contractor and supplier. |
|
|
|
|
James Eggert
Registered Users
Veteran Member
Posts:1059
|
| 09/02/2009 5:34 PM |
|
But that's just it, you don't want to "balance" the system is a true sense; you WANT something like a bathroom to have a toasty floor.
Look at it this way, the only way the loops will balance if they are all the same length is if the latent heat removed is the SAME PER LOOP! How will they guarantee that if say one room is over an unheated garage, or one loop has carpet versus tile.
I suggest you do some more radiant heat investigation, and then arm yourself with some good basics, before you get cold feet!
In a case like this, why can't they set up the bathroom(s) to be their own loop??
It doesn't sound to me like you are getting enough upfront feedback to let someone dancing do your system design!
|
|
Take Care
Jim
Design/Build/Consulting
"Not So Big" Design Proponent |
|
|
Green Build AB
Registered Users
New Member
Posts:14
|
| 09/03/2009 8:29 AM |
|
I am not obviously knowlegable enough about radiant heat and appreciate all the opinions and information on this site. I was told the temperature for the boiler is set at one temp. If the tube is all under one slab, it is one temp. If I add another application, like between the joists, the temp in the two "systems" is different. Therefore, a series of mixing valves have to be used to cool the water depending on where the water is going (under slab vs between joists. My thought was, the more water I need to cool a loop, the less efficiant it would become to heat water then cool it. I just do not know if this is the case or not and no one seems to be able to give me a straight forward answer. The system is designed with one boiler, two bathrooms would be supplied by the between joist pex and the rest is living space that will be supplied by in slab pex. I am just trying to find out what is the best way to put the tubes in the bathrooms (above or below the plywood subfloor) from an efficiency standpoint. Maybe there is no difference?
|
|
|
|
|
RadiantRob
Registered Users
New Member
Posts:10
|
| 09/09/2009 4:11 PM |
|
Green Build AB
You know what? If there is one thing radiant heat designers do best, it’s disagree...There are so many variables and so many different ways of installing a radiant heat system , or in your case a little add-on, that it’s easy to make a mountain out of a mole hill. That is exactly what is happening to your project. I’m not going to say you have to do something a “certain way” but I will say that a staple up is less expensive and probable easier, as long as the joists are still open. Make sure you insulate under the PEX well. The big question is, will your existing boiler handle the extra btuh capacity required by adding on the bathrooms? (most are oversized anyway) How is the boiler piped right now? Is it a primary secondary loop system? Do you know what the supply water temperature is? How do you plan on zoning it? You know there are a lot of, single temperature systems, out there that are being used to heat tubing in slab, or staple up or thin pours. Eggert mentioned increasing the number of loops to increase the amount of btuh supplied, for instance, going from 12” on center to 8” or 6” on center, increases the amount of tubing under the bathroom floors, this equals more btu/hr/sf, or “more heat”. There’s lots of ways to get the results you want, but it’s all give and take, you do staple-up and you loose a little efficiency, you do thin pour and you increase the cost of the job.
|
|
RadiantRob
Radiant Heat Designer
http://www.radiantdirect.com |
|
|
Blueridge company
Registered Users
Basic Member
Posts:211
|
| 09/09/2009 5:49 PM |
|
So,
Rob is right, there are so many ways to hit a radiant system, I would advocate a surface mount system if possible, You did not mention the square footage.
I had one client that used wonder board, our RHT 3/8 pex, and filled in the space between the wonder board with mortar, tiled over. he used romex staples to hold the pipe as they have a nearly flat head and take up little additional height, staples are captured in mortar. This worked well. We also have a 3/4 ply wood system, RHT floor panel system, as described it will use 3/4 inch. Staple up is great but it is less direct, more heat to push through the different layers of insulation. higher delivered temp. You will want heat transfer plates if your up in Alberta, another good argument for surface mount.
Good luck,
Dan
|
|
Dan
BlueRidgeCompany.com |
|
|
NRT.Rob
Registered Users
Advanced Member
Posts:733
|
| 09/09/2009 8:07 PM |
|
| there is also no guarantee that your bathroom slab will need a similar temp to your lower slab. That depends on a heat load: if a calc hasn't been done, then it's all just guessing. I have seen many joist systems work with a single temp in conjunction with slab as well. |
|
-=Northeast Radiant Technology=-
NRTradiant.com |
|
|
ecobuilder
Registered Users
New Member
Posts:86
|
| 09/09/2009 8:18 PM |
|
All good points, but if cost and height are the factors then under floor is less expensive and has not impact on your hieght. Yes it is slightly less efficient. As far as cooling down the water to accomdate the slab verses under floor this really isn't an issue. A simple mixing valve on the slab side of the system will do the trick. You are not adding cold water to cool the temp down you are simply adding less hot water to get the lower temp you want. You will have to set your boiler to the higher temperature setting for the under floor system. Under floor systems here in MA typically range from 120-130F and slabs range from 90-100F. I myself would install this under floor unless you are remodeling the bathroom and want to rip up the floor anyway. Save your money and put it into other areas of your home that will have a much greater impact on your energy consumption.(IE Insulation). It sounds as though you need a new heating contractor that is familiar with radiant systems and can guide you as to the best, most cost effective approach for your region.
Tom Pittsley
ecobuilder@aol.com
www.eebt.org |
|
"Don't be afraid to go out on a limb. That's where the fruit is." Jackson Brown |
|
|
NRT.Rob
Registered Users
Advanced Member
Posts:733
|
| 09/09/2009 8:29 PM |
|
| mixing systems add cost and pumps and lower efficiency for many heat sources. Though I agree that if this were an otherwise unnecessary retrofit, the cost of ripping up and replacing tile would be far greater than the cost of mixing, if that is not the situation, avoiding mixing is very nice. |
|
-=Northeast Radiant Technology=-
NRTradiant.com |
|
|
Green Build AB
Registered Users
New Member
Posts:14
|
| 09/09/2009 10:37 PM |
|
Thanks, these are all great replies. I agree that I could use a new heating contractor. Unfortunately radiant outside of the basement slab is rare around here and so many of the contractors no little about other applications. The boiler is not plumbed yet. I was recommended a Hamilton Evo HW 79. This boiler is rated for 80 000 btu/hr. The system as designed has a total load of 39000 btu/hr with a totla radiant load of 32 000 btu/hr. The system has 6 zones on 3 manifolds. This is a new build, not a retrofit. Square footage in one bathrrom is 110 square feet and the other is 77 square feet. The temperatures on the specs run 87 to 93 degrees fahrenheit. Height is probably not an issue. Total heated area is 3000 square feet. I think the supply temp is around 65 degrees fahrenheit. Plenty of insulation.
No one said anything about the Pex-AL or equivalent products. Any benefit? Thanks for the input. |
|
|
|
|
Blueridge company
Registered Users
Basic Member
Posts:211
|
| 09/10/2009 10:35 AM |
|
I hate to be the one to throw the curve ball but,
Why are you not heating the whole house in floor,
Its new construction. I understand you will probably have an air side as well for cooling, supplemental heating and air filtration.
Next why not purchase a prefabricated boiler pump distribution panel that your heating contractor can plug in,
last if you are only doing the bathrooms are you not placing a wonder board down for your tile,
Lay the 3/8 pipe in that, capture pipe with mortar, done on top.
Dan |
|
Dan
BlueRidgeCompany.com |
|
|
RadiantRob
Registered Users
New Member
Posts:10
|
| 09/10/2009 10:56 AM |
|
Can I give you a little advise about the EVO HW 79? That type of boiler has a horizontal heat exchanger in it. It’s essentially a 5/8” stainless steel pipe that’s partially flattened then rolled into a tight coil. The burner is stuck in the middle of the coil, then water is circulated through the coil, where it pick up the heat from the burner and exits the other end. I can not stress enough how important “proper flow” through this type of heat exchanger is. If you choose to go with this boiler, make sure your installer knows how to build a “primary/secondary” piping configuration. I have seen, to many times, where the lack of flow has caused hot spots in the top portion of the heat exchanger, resulting in pitting and leaking. No manufacture will cover a warranty if the system wasn’t piped properly in the first place. Secondly, the type of heat exchanger in this boiler creates a lot of head. I know of one manufacture that uses this heat exchanger and requires a Taco 0011, or equivalent, just to maintain proper flow though the boiler. That’s an 1/8 HP pump! Thirdly, cleaning… you may be required to clean the heat exchanger yearly, which is a major job, since a major portion of the boiler needs to be torn down just to get at the heat exchanger. You may even find that you have to replace some gaskets each time this is done. (Another added expense)
BTW, Who did your heat load calculation on your house? And is it a ICF home, or similar?
|
|
RadiantRob
Radiant Heat Designer
http://www.radiantdirect.com |
|
|
Green Build AB
Registered Users
New Member
Posts:14
|
| 09/10/2009 10:02 PM |
|
Had considered heat for the whole floor. However, my heating contractor convinced me to use forced air upstairs since I have to run ducting for the HRV anyways. Would I need to place wonder board. I was planning on usinf Ditra so thought it might not be necessary, especially if putting the tubes above the sub.
Uponor did the heat calculation. I have ICF in the basement and will be using spray foam upstairs. It is a walk out bungalow.
RadiantRob, I sent you a PM. Thanks |
|
|
|
|
Green Build AB
Registered Users
New Member
Posts:14
|
| 09/11/2009 6:56 AM |
|
| I have seen several references in postings elswhere about a "sandwhich" technique. NRTRob posted a picture of it once in a thread. But what is it exactly. The picture looked like tubes and transfer plates. What is the sandwhich part. Thanks |
|
|
|
|
NRT.Rob
Registered Users
Advanced Member
Posts:733
|
| 09/11/2009 9:05 AM |
|
Primary/Secondary piping is a good way to guarantee proper flow through a boiler. However, it's not the only way, and it adds pumping that is basically wasted. While your contractor should be aware of primary/secondary, it's not the only game in town.
That said, the flow/cleaning issues are a big part of the reason we recommend the Triangle Tube Prestige solo line. much less flow sensitive, pretty low pressure drops, easy to clean.
Sandwich is plywood strips with light or heavy gauge plates and PAP or PEX pipe, depending on plate type. it's called "sandwich" between it sandwiches the pex and aluminum between the subfloor and finish floor. it's cheap material/high labor, and good to great output depending on plate type... better than most of the wimpy panels out there with lightweight plates, and in the same league (but not quite as awesome) as Warmboard, Roth, and Raupanel with the heavy plates. |
|
-=Northeast Radiant Technology=-
NRTradiant.com |
|
|
RadiantRob
Registered Users
New Member
Posts:10
|
| 09/11/2009 11:07 AM |
|
|
Do you even need A/C up there? Why don’t you just open a window?
|
|
RadiantRob
Radiant Heat Designer
http://www.radiantdirect.com |
|
|
Green Build AB
Registered Users
New Member
Posts:14
|
| 09/11/2009 1:55 PM |
|
No AC planned. For the couple days a year when I may need need, I do not think it will be worth the expense.
|
|
|
|
|
Blueridge company
Registered Users
Basic Member
Posts:211
|
| 09/11/2009 5:19 PM |
|
With no ac, unless you have air sensitivity issues and need air filtration I would lean towards a condensing boiler and going for the full in floor heat. You are already 1/2 way there with the basement slab, all you are doing is creating an upper floor zone or zones.The in floor is a great improvement to a home both comfort and resale value. There are a few good boilers out there to chose from,others work well, We like the Neo them, Link ; http://www.blueridgecompany.com/radiant/hydronic/659/laars-tank-boiler-packages These have the primary loop pump built in, andwill ramp delivered water temp for domestic hot water heat exchanger or lower down for the in floor side.
Air to air movement can be accomplished with a Heat ventilation recovery unit.
Dan |
|
Dan
BlueRidgeCompany.com |
|
|
Robert Bean
Registered Users
New Member
Posts:2
|
| 09/11/2009 11:44 PM |
|
You may want to consider the attached document from Municipal Affairs and Housing – Safety Services – regarding design requirements for hydronic system in the province of Alberta.
rb |
Attachment: 06BCI012.pdf
|
|
|
|