Radiant Ceiling

Jeff Perry_3

Application: Historic house with plaster ceilings. Crown molding in every room so the ceiling isn't coming down nor can it be lowered with radiant panels and new layer of sheetrock. We have access above. Anyone have thoughts on different ways to do a radiant ceiling from above and what type of panels and attachement methods?

Thanks

Jeff Perry

Gordy

Old Lath, and plaster.

  Have you actually looked at the surface texture of the the ceiling from above?  Seems to me that if its is wood lath with plaster construction, it would be real challenge to get some sort of good contact with plates, and tubing. Being that the plaster over burden that pushes through the lath upon application of the brown coat would keep the plates from getting full surface contact a MUST!



  If its somethig from the 50's ( which I doubt would be considered historic).  Mine has what is a celotex type of panel with plaster to that, your challenge will be fighting pushing through downward rvalue of that material.



So first question is what conditions do you have above?





Gordy

Mark Eatherton

Curious...

Is this in Poughkeepsie?



ME

Jeff Perry_3

Poughkeepsie?

What the heck are you doing in, or know about, Poughkeepsie, Mark? No, Poughkeepsie was in the area of my old stomping grounds. I'm in VA now away from the snow.



jeff

icesailor

Radiant Ceilings:

For what it is worth, I have an account that is like what you are describing. It is an old 19th Century home that is like a museum. In the late 50's, early 60's, this was an option. The house was a gut re-hab. They nailed Gypsum "Rock Lath" to the strapping, stapled up 1/2" OD copper tube and plastered it over with Structo-Lite as a brown coat and used a lime plaster as a hard finish. It works very well. They insulated above the panels. At some point in the past when I wasn't involved, something happened to some of the ceilings and they had to be repaired. The panels were cut down. They cut along the antique crown moulding and butted the rock lathe to the cornice moulding. They replaced it all with some type of PEX tubing. They then just plastered over the PEX coils. All has been well and good. Even to the fact that the person who did the heat prior to me (they are plumbing customers, now I do both) the heater person replaced the Smith-Mills Series 2000 6 section hot water boiler with a Weil-McLain WGO-6 which is in no way, large enough to heat the building in the winter. But the heat is left at 50 in the winter and no one lives there but the heat is on and the water is drained. It had 7 zones of tempered radiant water that went through a SPARCO thermostatic mixer with a mechanical outside sensor to adjust the hot water radiant temperature. If the return water went over 150 degrees, all seven circulators would stop and let the system radiate. There were three high temperature zones and a tankless heater in the boiler with a 75 gallon copper hot water tank. (I knew the house in the past as I worked for the previous owners.) The high temperature water return water entered the boiler through a separate connection.  All supplies and returns now are connected together. The mixer was removed and an indirect was installed. All heat that goes into the system is as hot as whatever is needed. 180 degree water is not beyond the realm. The previous "heater" had a problem with the second floor over heating. The solution was to clip the wires on the old MH832 relay so the circulator wouldn't run. He also filled the system with antifreeze that now tests to about +20 degrees. I have never added water to the system. The water looks like coffee. It has bothered me a lot. But I don't want to start something that has no solution. While relating this, I suddenly realized where all the rusty stuff is coming from. The new PEX isn't an oxygen barrier tubing and is letting oxygen into the system.

What a mess.

So to answer your question, you could install radiant in the ceiling of an old antique house and leave the mouldings. There are actually a series of photographs taken and mounted on a board in the house that show where all the lights are and any important landmarks. If you are truly interested, and the customer really wants to go this way, I could try to photograph the radiant PEX repair/install. You don't need plates to reflect the heat. If the above ceiling space is heavily insulated, it will work fine without them. There is only that old insulation in the dark brown bag in the ceilings. I doubt that it is 3". More like 2.5". And you can run a radiant ceiling a lot hotter than a floor.  

Mark Eatherton

Poughkeepsie...

I have a friends daughter looking for assistance on a radiant ceiling there. I was told to contact Bruce Perry, and I automatically (maybe wrongly so) associated you with him.



Not related?



How is it Va is missing all the storms?



ME

CMadatMe

It's His Brother ME

Bruce is Jeffs younger brother..Guess who the kid in the pic is

Mark Eatherton

Thanks Chris...

Looks like they've been turning and burning for a while :-)



ME

CMadatMe

1927

Since 1927....

LarryC

thermally conductive thinset?

Non heating professional speaking.



Does anybody make a thermal conductive thin set?  If the ceiling could support the additional weight and the tubing was hot enough, would this work?

 

Perhaps a graphite bearing or metal threaded mesh cloth to spread the heat from the emitters and the thin set to bond the cloth to the plaster.  Obviously good insulation is required above to direct the heat downward.

hot_rod

what output

are you chasing? You could do the old suspended tube method from above, if you are looking for a warming system. Fasten the tube just off the ceiling joist and insulate above it. A joist bay convection system of sorts.



If you have an old Wirsbo Complete Design Assistance Manual 4th edition circa 1999 you will find a lot of data on joist heating in chapter 5, including an output chart showing about 18 btu/ sq. ft with 8" oc spacing and 140F supply temperature, and a suggested max temperature of 180F.



Some of that old plaster can be toxic. They blended horse hair in the mix for strength and the horse hair was at one time stripped from the hides with arsenic.



There have been articles in JLC and Fine Homebuilding and other magazines about the hazards of working around that old plaster. I would disturb it as little as possible, and have it tested if you do end up removing or cutting some for repairs.



hr

Gordy

Plaster keying

 What ever you try do not attempt to remove any of the keyed plaster between the lath to promote a smooth surface.  That is what is holding the plaster to the lath.



 I like HR's idea if it is low load. Sounds not to labor intensive, and less evasive.  Not a bad output for 140* water temp.  If the ceiling height is not to much.



Gordy

Big Ed_4

Radiant Ceilings

Most of the radiant ceilings I have see , just a few mind you , was embedded in the cement backing of a plaster ceiling ... Would make sense to me to lay the tubing out and use a light weight cement to cover the tubing ....

Gordy

Original Post

 That's how mine is Big Ed, but original post indicated that there is crown moldings that they did not want to remove etc. They are looking for a back side alternative. Which will give a lot less performance than an embedded type. 

icesailor

Radiant Ceiling:

And I said earlier, I have an account with a plastered radiant heat system in the ceilings in a museum type antique house. With custom antique irreplaceable mouldings and antique wall paper. Some lubes leaked, they cut the plaster beside the mouldings and didn't remove the mouldings. They replaced the copper tube with PEX. They re plastered the ceilings. It looks like it never happened. There are photos on the job from when they did it.

It works.

Gordy

Read it

 I could see doing that IF the ceiling was in dire need of repair, or no other means of providing another type of heating system. Not so sure about pex in embedded in plaster though much different expansion rates in the 2 materials. I know you said it worked there. May be short tubing runs or small areas. 

icesailor

PEX Ceiling:

Gordy,

The PEX was used to replace the copper in five rooms. It was laid up exactly as the 1/2" OD copper was. It was done over 10 years ago as far as I can tell. There are no signs of cracks anywhere in the affected ceilings.

I would never have recommended it if I was asked. Because I saw and see this repair on a regular basis, I am telling you about it. It may be a bad idea for another reason and that is that I was wondering why the boiler water was so bad. I think that the reason is that the PEX tube isn't an O2 barrier tubing and O2 is getting into the system. I hope I either retire or the owner sells the house. I don't want to explain to the customer the reason their heating system has failed. It has already failed in some rooms and it was replaced with baseboard. The previous mechanics were mostly clueless about the workings of the system and really messed it up. It is probably beyond repair. I don't want to be the bearer of bad tidings.

rlaggren

Trade off between new plaster ceiling and new floor

My mother's home had the same repair (sans heating) that IceSailor has described. Admittedly we had one of the two best plaster guys in Chicago doing it (I know because there was crown molding repair involved as well and only two guys would bid on it... the insurance company freaked out ). But he viewed cutting out the ceiling field and replacing with rock-lathe as a non-issue; the real problem was the busted up crown molding that needed replacement.



So I don't think the crown molding per se is necessarily a road block - the plaster guys can leave it alone and work around it. Whether the heating guys can work around it is another question...



One note: My plaster sub insisted that his men were the only ones to touch that ceiling plaster. He did all the demo (whole ceiling came down except the remaining good crown). His bid was based on replacing a certain amount of crown and he did NOT want to have to do any more than that, so he wanted his tradesmen familiar with plaster to cut the ceiling away w/out damaging the good crown. If you consider going with a new ceiling, you should let the plaster sub assume full responsibility for the plaster - ie. let him take the old ceiling down as part of his bid.



Rufus

icesailor

Radiant Ceiling Mouldings:

For some clarification, the ceilings I am writing of has wood mouldings. I believe that Rufus is writing about Plaster Of Paris mouldings. Way back when, when I started out, I worked for a Mason and we did plaster ceilings. I worked on more than one ceiling that we took down and replaced. We never did a radiant ceiling but there were a bunch of them going in. We just never did one. But we cut out a few along the mouldings. Never a problem if you were careful. And we didn't have the tools of today to work with. We didn't have drywall screws back then.

Gordy

Good plaster hard to find

 Now days.  I have a friend who does plastering, he is very good does the moldings etc. T&M only on the moldings.  Good advice Riaggren. Last thing you want is a pissing match between plasters wanting more money because demo did not suit them.



 I love my radiant ceilings which are the 50's style ( 3/8" copper tubing embedded in plaster 6-8 inches oc) Very responsive, and powerful with a medium amount of mass. The back losses are not what you would think either. Very even heat, and no worries about floor coverings, furniture etc blocking output. Save the floors for basements, kichen tile, and baths. Liquid sunshine.



Gordy