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Radiant Floor Heat Not Warming House

luddite20's picture

Radiant Floor Heat Not Warming House (post #205671)

luddite20 on Tue, 01/24/2012 - 18:34
in

Ok, I'd love some advice here.    I recently installed a hydronic heating system in my 800 sq. ft.  home here in Berkeley, CA.  I have a 1941, run-down, fixer upper with hardwood floors throughout most of the house.   I ran about 1000' of Pex tubing between the floor joists and stapled it up with aluminum transfer plates.  I built a manifold that runs off of a tankless water heater that ties both the domestic hot water supply and radiant floor together (open loop---hot water that comes out of shower first goes through floor---this system is very similar to one created and sold by Radiant Company in Vermont.)  In terms of insulation, I stapled up an ecofoil radiant barrier about an inch below the pex, and R-19 fiberglass below that in every area except my bathroom, which is currently leaking from the shower drain and therefore left uninsulated until I can attack that project.  The home has been seismically retrofit, and there is no insulation behind the sheerwall.  I tried to leave a tail on the end of the insulation to bring over the rim joist, but it's not that tight, and the crawlspace itself is vented.

And.....the attic has Zero insulation at this point (as of today I am in the process of updating the knob and tube that runs through the attic in order to insulate.)

Now, I have the system under 1 zone with 4 seperate loops of about 250' each.  Now here's the problem.  My house doesn't seem to be able to get above 67 degrees, and that's if I let it run for 24 hours.   If I do let it run for 24 hrs, I'm using around 4 therms, which, in my humble opinion, is far too much for 800 sq. ft.  

Is anyone willing to lend an ear?  I have invested a lot of hard time into this here project, and currently feel as though I've failed.  Ex post facto, I don't believe radiant floor heating is ideal in this climate, but at this point this is neither here nor there.  I was really excited to install this and here I am. 

 

Help?!!!

-A +A

and most importantly, my wife (post #205671, reply #1 of 30)

by luddite20 in reply to luddite20 [original] on Tue, 01/24/2012 - 18:36

and most importantly, my wife is cheap and cold.

additional info (post #205671, reply #2 of 30)

by luddite20 in reply to luddite20 [original] on Tue, 01/24/2012 - 18:48

Also, the supply temp is 125F.  I had it set at 135F but then I noticed the floor boards I recently refinished were cupping/seperating!!!  Return temp is 114-117.  So temp drop is around 20 degrees.

The 4 loops run off of a 3/4 pex header.

Well, first, no need for the (post #205671, reply #3 of 30)

by DanH in reply to luddite20 [original] on Tue, 01/24/2012 - 18:53

Well, first, no need for the double post.  Every post gets read by just about everyone.


We are like tenant farmers chopping down the fence around our house for fuel when we should be using Nature's inexhaustible sources of energy -- sun, wind and tide. ... I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that. --Thomas Edison

How was the house heated (post #205671, reply #4 of 30)

by DanH in reply to luddite20 [original] on Tue, 01/24/2012 - 19:01
  1. How was the house heated previously?
  2. How do you balance the loops?
  3. Describe your loops and pump arrangement a little better.
  4. Oil, propane, or natural gas?


We are like tenant farmers chopping down the fence around our house for fuel when we should be using Nature's inexhaustible sources of energy -- sun, wind and tide. ... I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that. --Thomas Edison

Hi Dan-   the house was (post #205671, reply #10 of 30)

by luddite20 in reply to DanH [original] on Tue, 01/24/2012 - 20:44

Hi Dan-

 

the house was previously heated by a single floor heater in the main room.  The loop is only balanced by the fact that they are the same length.  The loops are each 250'.  The manifold design is attached here.  I am using Natural Gas.  And I really appreciate your input.

 

As for the manifold, domestic hot water is essentially taken from the floor, and cold water replaces it from the municipal supply.  I chose this method over others so as to never have stagnant water, and I was concerned about actuators failing with the traditional manifold method I've seen.  thoughts?  suggestions?

 

chad

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What temp do you manage to (post #205671, reply #12 of 30)

by DanH in reply to luddite20 [original] on Wed, 01/25/2012 - 05:14

What temp do you manage to achieve on the outgoing heating loop -- seems to me you'd be dragging a fair amount of cold water through the loop with that piping scheme.


We are like tenant farmers chopping down the fence around our house for fuel when we should be using Nature's inexhaustible sources of energy -- sun, wind and tide. ... I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that. --Thomas Edison

Inadequate Insulation (post #205671, reply #5 of 30)

by KDESIGN in reply to luddite20 [original] on Tue, 01/24/2012 - 19:55

If you are using too much energy and not getting enough heat for the house, it sounds like the insulation is inadequate.  If instead, the problem were with the heat distribution system being unable to deliver sufficient heat, then you would not see excessive fuel usage. 

thanks Kdesign.  I'm assuming (post #205671, reply #6 of 30)

by luddite20 in reply to KDESIGN [original] on Tue, 01/24/2012 - 19:59

thanks Kdesign.  I'm assuming that once the attic is insulated things will improve, but at what level I am unsure.  Perhaps I should hit the rim joist with one of those 2 part expanding foam kits?

again, thank you.

All the insulation has to (post #205671, reply #7 of 30)

by KDESIGN in reply to luddite20 [original] on Tue, 01/24/2012 - 20:23

All the insulation has to work together, so it is hard to comment without seeing exactly how it is all set up.  What type of insulation is in the walls?  What thickness is it?

ah, now we get to this. (post #205671, reply #8 of 30)

by luddite20 in reply to KDESIGN [original] on Tue, 01/24/2012 - 20:29

ah, now we get to this.  There is nothing in the walls, as is all too common in Berkeley.  I've thought about cutting in the the walls and blowing down, but there is the attic to contend with first.  

First thing to do is to seal (post #205671, reply #9 of 30)

by DanH in reply to luddite20 [original] on Tue, 01/24/2012 - 20:37

First thing to do is to seal the air leaks.  Likely there are spots where you can see daylight.


We are like tenant farmers chopping down the fence around our house for fuel when we should be using Nature's inexhaustible sources of energy -- sun, wind and tide. ... I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that. --Thomas Edison

Thanks Dan.  In the (post #205671, reply #11 of 30)

by luddite20 in reply to DanH [original] on Tue, 01/24/2012 - 20:45

Thanks Dan.  In the crawlspace the only visible "daylight" air leaks I can see are through the vents initialy placed down there.  As for the attic, I have daylight at the eve and obviously through the louver vents I installed when I re-roofed the house.  I have a temp gun, would that help with diagnosing temp loss in the crawlspace?

Use the temp gun from above, (post #205671, reply #13 of 30)

by DanH in reply to luddite20 [original] on Wed, 01/25/2012 - 05:16

Use the temp gun from above, pointed at the floor and baseboards and lower walls, looking for air infiltrating from below.  Also check electrical outlets.


We are like tenant farmers chopping down the fence around our house for fuel when we should be using Nature's inexhaustible sources of energy -- sun, wind and tide. ... I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that. --Thomas Edison

the only thing to talk about here (post #205671, reply #14 of 30)

by NRTRob in reply to luddite20 [original] on Wed, 01/25/2012 - 08:39

is how to insulate.  4 therms at  80% efficiency and 800 square feet is only a sustained heat load of 16 BTUs/sq ft.  If anything, I'd say that was low for an uninsulated building, even in your climate.  Congrats, you're getting off lucky.

insulating will of course reduce this significantly.

-------------------------------------

-=Northeast Radiant Technology=-

Radiant Design, Consultation, Parts Supply

www.NRTradiant.com

Exactly Radiant heat isn't (post #205671, reply #15 of 30)

by xxPaulCPxx in reply to NRTRob [original] on Wed, 01/25/2012 - 10:37

Exactly

Radiant heat isn't like forced air, where you feel a direct effect... it's alot more gentle, and better suited to a house where a good sealing and insulation system works in conjunction to create an even heating effect.

Do the air sealing and insulation, then you get to come back and complain if you don't think your heater is working up to snuff!

YAY!  I love WYSISYG editing!  And Spellcheck!

____________________________________________________

Ok.  But I hope my post (post #205671, reply #17 of 30)

by luddite20 in reply to xxPaulCPxx [original] on Wed, 01/25/2012 - 10:45

Ok.  But I hope my post didn't seem like a complaint, but a call for help.  This work is new to me, and I just want to make sure I do things correctly, as there is no one here helping.  Much obliged to everyone's input.

 

Thanks rob.  I appreciate all (post #205671, reply #16 of 30)

by luddite20 in reply to NRTRob [original] on Wed, 01/25/2012 - 10:42

Thanks rob.  I appreciate all the input.  Once the knob and tube is replaced I'll go R-30 in the attic as per code and see how that helps.

 

chad

that will probably knock a (post #205671, reply #18 of 30)

by NRTRob in reply to luddite20 [original] on Wed, 01/25/2012 - 10:56

that will probably knock a quarter off.

doing the walls would probably knock off another quarter or so.  Just round guessing but should be a ballpark.  of course the usage per day varies based on how cold it is outside.

-------------------------------------

-=Northeast Radiant Technology=-

Radiant Design, Consultation, Parts Supply

www.NRTradiant.com

You need to do a heat loss (post #205671, reply #19 of 30)

by srb2020 in reply to luddite20 [original] on Wed, 01/25/2012 - 20:35

You need to do a heat loss calculation with all of the proposed future insulation you plan to install.  That should give you a really good idea if it is ever going to work.  800sqr ft is not a lot of radiant surface to overcome the kind of heat loss you describe.  There are some great on line companies that can do that for you but they need complete plans and specs (they'll tell you exactly what they need).    My 800 sqr ft bungalow in climate zone 6 did not have enough surface area (in the floor) to consider radiant floor heat.  The high number of windows was also a factor.  In your climate zone it might be ok once you've insulated but you really need to do a heat loss calculation.

 

Good luck.

thanks srb.  any companies (post #205671, reply #21 of 30)

by luddite20 in reply to srb2020 [original] on Wed, 01/25/2012 - 21:53

thanks srb.  any companies you'd recommend?

 

chad

Personally, I think its nuts (post #205671, reply #22 of 30)

by sapwood in reply to luddite20 [original] on Thu, 01/26/2012 - 08:43

Personally, I think its nuts to do anything at this point other than insulate. A ways back in this discussion you asked if spray foaming a rim joist would do any good. That's simply goofy without first addressing the walls and ceiling. You've got the radiant system installed so there's no point in now doing the design for it. I wouldn't be distracted from the primary goal. Reduce heat losses first. Spend your money where it will do the most good.

thanks sapwood.  I think (post #205671, reply #23 of 30)

by luddite20 in reply to sapwood [original] on Thu, 01/26/2012 - 09:05

thanks sapwood.  I think you're right, and I'm on it.  I just wanted everyone's thoughts too.

It may be goofy and then (post #205671, reply #24 of 30)

by cussnu2 in reply to sapwood [original] on Thu, 01/26/2012 - 12:00

It may be goofy and then again it may not be goofy.  I saw on here or Green Building Advisor a case with radiant flooring that wasn't performing up to standard and in that case they found that the loops were in contact with uninsulated rim joist in each bay.

I'm hoping he knew......... (post #205671, reply #25 of 30)

by calvin in reply to cussnu2 [original] on Thu, 01/26/2012 - 12:31

That it's wise to run to the most heat loss areas first-outside walls etc, then work your way back to the return.

DIY is fine and I commend anyone for trying (like most, I've DIY'd many things I'm not adept at), but-design and spec'ing a heating system is not fly by the seat of your pants.  Once he stuffs the heat loss points and insulates, I hope his dreams of wonderful radiant heat, are realized.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 

calvin- I"m a persistant (post #205671, reply #26 of 30)

by luddite20 in reply to calvin [original] on Thu, 01/26/2012 - 12:59

calvin-

I"m a persistant bastard, so I will keep at it.  I am going to first finish re-wiring attic for that to be insulated.  Then walls when I get a chance.  As for the rim joists, my loop ends were help back 18" from them to minimize heat loss through that area.  I really appreciate you help.

lud (post #205671, reply #27 of 30)

by calvin in reply to luddite20 [original] on Thu, 01/26/2012 - 13:16

Persistance in the face of defeat wouldn't be smart.  But then again, this isn't the bighorn.  I'm sure you'll get this working to your satisfaction.

 

One question tho-here with the slab-we ran tighter spacing around the perimeter for that reason-heat loss.  Rather than avoid it because of heat loss-we increased the amount of hose to make up for it.   Now, I've got and inch and a half foam between the block foundation and the slab-I still find cool concrete beyond the hose-not bad, but a noticable difference in toe temp.  I wonder if you shouldn't have pushed that hose closer to the band.   Did you run tighter hose spacing where you could (parallel joist/foundation/band)?

I'm thinking that the comparison between running in slab and between joists is not really applicable.  But it's just a thought.

Rob is pretty sharp with this stuff, hope he's here to offer further info.

 

Best of luck!

and please, report back-those of us that read this stuff hate to miss the next chapter.

 

thanks.

 

EDIT:   Well let's see-sexism in the word filter?

Persistant bastard?          Persistant [CUTE LITTLE PUPPY]?

 

What's wrong with that picture?

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 

Persistance in the face of (post #205671, reply #28 of 30)

by luddite20 in reply to calvin [original] on Thu, 01/26/2012 - 13:22

Persistance in the face of defeat?  Jeez, that reminds me of my wife.  Before I throw in the towel I have to insulate at least the attic, which has nothing at this point.  As for the loops, they are built off of parallel headers.  I used 1/2 pex and 1 loop per bay (2 1/2" lines per bay).  I used 1/2 because of workability in such a tight crawlspace.  I didn't want to put the loop ends any closer than 18 inches from rim joist even if I do really go at it with more insulation, as I was worried that even with that insulation, the fact that the shear walling is covering up non insulated areas about the sill place would render the rim joist insulation moot.  I will keep you all updated, whether it's a success or walking to the gallows.

when you mention "rob", do (post #205671, reply #29 of 30)

by luddite20 in reply to calvin [original] on Thu, 01/26/2012 - 13:24

when you mention "rob", do you mean NRTrob?

 

chad

Chad (post #205671, reply #30 of 30)

by calvin in reply to luddite20 [original] on Thu, 01/26/2012 - 13:29

yessir, NRTrob.

 

And what the heck-I thought you were living in California?   You need heat in California?

Why the hell would you ever settle down in California?

if you need heat.

 

 

But I digress.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 

    (post #205671, reply #20 of 30)

by srb2020 in reply to luddite20 [original] on Wed, 01/25/2012 - 20:37