Radiant cieling

Unknown

I'd start with a 95 min 120 max and go from there.

Dperg

Im Bidding a boiler replacment job with an existing radiant ceilng system and indirect water heater. The existing boiler piping does not have any mixing valves so it looks like they feed system with high temp water. What is the reccommended temp for this type of system. I plan on using a reset control.

Bruce_26

Am I Correct

in thinking that this is a 1940-1950 radiant ceiling system that has either copper or black pipe in the ceiling? If it is, the design temperature is usually 155 to 165 degrees with a return temperature of 30 degrees less. Remember that these old ceiling radiant systems were designed to run at a higher temperature than the radiant floor systems of that time period. This is a fine system that usually gives nice even heat. If it works well (and most do) pay close attention to the way it was piped and the type of circulator that was used. In my opinion, there is nothing finer than an old radiant ceiling system.

Terry Trommeshauser

high temp

even the newer radiant ceiling panels require higher temps than infloor. typically same as baseboard.
the Reset will work fine. add an indoor sensor to the controller and you'll be off to the races!

good luck!
Terry

Unknown

?????

We never, ever design a radiant ceiling for over 120. I have no idea where your claim is coming from.

Terry Trommeshauser

this is from my suppliers website:

Another reason for placing the panels in the ceiling is so that higher surface temperatures can be used. The rate of radiant heat transfer from the panel is governed by the Stefan-Boltzmann Law, q = S Ts4 , which demonstrates that the radiative heat transfer from a body increases dramatically as its temperature is increased. Radiant ceiling panels are typically operated at 79-85°C (175-185°F). On the other hand, were the radiant panels mounted on the walls or near the floor, safety code dictates that the panels could not be operated at high temperatures. Thus by placing the panels in the ceiling, the panels can be made to produce more output per area by simply increasing the water temperature.

Terry Trommeshauser

175-185F

opps. consider this one a bump

Unknown

that's a pretty poor practice, IMHO.

I have yet to find a room you can't heat with 120 with a radiant ceiling, other than massive commercial situations, assuming plates are used to conduct to the drywall.

That includes 11' tall nearly uninsulated rooms. 1.4 BTUs/sq ft/deg F surface temp differential.

If you're going to run 180 in ceiling, you're wasting most of the benefit of radiant in the first place... low temperature operation. and for no real benefit, because no residential space needs that kind of output... and in most cases, the owners will find it uncomfortable as well. That's a big reason why the old ceiling systems didn't take off.. hot head syndrome was pretty common.

maybe, in a 15' tall warehouse or something. in a house? never, and never needed.

tim smith

Regarding ceiling radiant temps

An old PE steam & radiant designer friend of mine always stated that for true metal lath & plaster ceilings, he figured the max design temps at 140 to prevent cracking etc, plaster & copper expansion rates fairly close he said. He has done many system designs over the yrs and well known around these parts. By the way, he's 94 now and just retired fully about 3 yrs ago. !_! This was with copper tube so I do not know how close the expansion rates are off hand to Pex so Pex may need to be lower due to higher expansion rate. Just a thought, Tim

Unknown

your supplier, btw, is selling ceiling radiators, more than "radiant ceiling"... very different tech. leveraging the full ceiling square footage (or really any major portion of it) results in much lower operating temperatures, same as radiant floor typically outperforms a panel radiator (until carpets are thrown on it).

Dperg

More info

I went back to the job today to investigate some more
It is a 2 pipe system that has been repiped with new 1-1/2" mains and 1/2"ball valves for each room.The only thing I see is that the mains and branch lines are and were copper.There is know access to view the actual heat admmiters that are in the ceiling. There is two controls on the boiler one set @ 180 the other set@ 160. I only let the heat run for 30minutes and recorded the supply temp reach over 130. The are crackes in a realitively straight line were the ceiling was the warmest.The original circ is a GE 1/16hp, 1425rpm@2.6 amps. I think to be safe A mixing valve should be installed hopefully lower temp so the cracks wont get any worse but I dont want to sacrifice comfort

Derheatmeister

Lower the Temps!

I agree with NRT.ROB about the usage of lower temps on a radiant ceiling.

One shall not "Bake the ceiling"

It apparently will "Crystallize" the Sheetrock/Paster.And Insulate it's self....

I did one 4 years ago and used lower temps for mine to avoid the hot head, cold feet syndrome.

So far no complains of uneven heat or cracking ceilings.

looking at the Pix : it looks like some one did some Re piping not to long ago? Propress? maybe they removed a Mixing valve because they did not know what the "Dead men" did and thought it was not needed?

Maybe you can(Just on a temporary experimental Basis,since you are planing on a repipe anyway) Just lower the Boiler temp to say 110/ or 120 F

I know the boiler will Condense but Looking at the equipment it needs out anyway,

If your customers home heats with the lower temps then all power to you!! Try a Modcon.Just some Thoughts..Richard from Heatmeister..

Dperg

I'LL Try it

Unfortunatly heating season is going away or should i say fortunately. So the only real test will come next heating season. I looked @ some mixing valves there max temp is 150
So I will have some room to play. They just replaced oil tank So Im going to use the buderus 90% boiler. It will be my first install with the G125BE.

Bruce M_2

Date of Original Installation

Where you able to find out the date of the original installation? Some people are confusing current practices with an installation from the 1940's and 1950's. The system would have originally been designed to use the higher temperature. It will not give you "hot head cold feet". Think about the sun; are your feet cold when you are standing in the sun? You might ask around for a very old plumber who is retired and you will get a better understanding. Another good source of information is here in the library. There is a section with old radiant literature and it will most likely explain things.

Terry Trommeshauser

Sorry Rob

Sorry Rob, I was referring to commercial ceiling "panels" which we install in schools and other commercial aps.
and up here in the great white north (it sure is today), we need the high temps to get the heat we need.

I guess I chimed in too early, as I now realize that this job is a residential app with plaster ceiling.

my bad.

Derheatmeister

Engineering Facts!

Please check out Wirsbos Complete Design Manual:

DO NOT exceed 120F water temperatures with radiant ceiling,streaking and hot-head/cold-feet syndrome may develop. Because of its powerful output,it is not always necessary to install radiant ceiling over the entire ceiling area.

Also: try to limit the BTU/h/ft to a maximum of 46 btu,beyond 46 btu/h/ft the system exceeds the surface temperature limitation for an 8-foot ceiling.

Did you not say that you have cracked ceilings?
130f may be to high...

And to Bruce:I do not think that the pyshics of Radiant Ceilings Changed in 50 years.Did gravity?

Thanks to the "dead men" we now know that we do !

Dperg

I only had an 1/2 hour to let the system to get to 130. Under normal use Im sure it gets up to 180 thats what the control was set at Plus there was an indirect instaled off the main system piping. with no evedince of any mixxing.
I believe the house was built in 40s 50s. Ive done a lot of research in the heating helps library and found a lot of info. Im going to figure using a mixing valve. The next issue is pump sizing There is now access to any heat emmiters whats so ever. The only clue are 1/2 copper branches feeding each room with new ball valves.Im going to drain the furthest room to measure how much water it holds So I can figure the head needed. I really appreciated all the input from everybody

Gordy

52 Radiant ceiling

I have a 50's Ceiling radiant system. 3/8" copper tubing inbedded in the plaster 6" on center through out the ranch.

Original Taco paneltrol mixing valve (see the walls library). System parallel piped. Listen to NRT Rob my system has never seen temps of over 115* supply with 95* return been that way since its installation.

Still have the original Chase copper tubing literature. They do state in the literature 160* supply temps are possible but WHY if you don't need to. I never have the hot head syndrome that people seem to believe.


I think someone repiped, and ditched the mixing valve, or maybe the dwelling HAD a high heatloss with the need for higher supply temps.


Gordy

Gordy

P/S

A big help for me was an infra red thermometer in tracing down the ceiling piping. Draining, and measuring volume is better yet.

If your piping is 1/2" maybe your ceiling pipes are 1' on center which may indicate higher temps needed. But not that much. Usual practice was 3/8" tubing in the plaster though.

Gordy

Alan_11

bypass loop

Is that a loop between the return and supply ,bypassing the boiler, with a gate valve that is partially open ?

Dperg

Yes I beleive its a bypass loop But was closed completely

Unknown

np, I know how exciting it is to get to talk ceiling since most people halt at "heat rises"

Derheatmeister

Bypass loop

I was looking at the"bypass" Loop as well, if the Bypass is completely shut i would readjust it so that the supply is some were around the 110F and the returns at the 140F minium, (if possible ....)

This bypass is Not really the proper way to lower the supply temp

I would recommend installing a Injection system based on outdoor reset/ boiler protection or using a 3 or 4 way mixing valve.. if you are going the cast iron route ,then i think that they have a "Plug and Play setup for this situation. good luck.. Heatmeister

Dperg

The Plug and play systems offered are nice but I dont think the circ that comes with them will give me enough head. Its a 2 story house Im guestimating about 30+ of head. Im headed out tomorrow to drain the longest branch so I have a better idea.

burninben

cieling heat

I recently did an in cieling job. House was about the same age. The difference was mine had an old wiel mcclain instead of an american standard. I am not at home by my computer but I will post pics when I get home. I have the befores but not the afters yet.