converting radiators to hydronic

DiyEverything

Hello everyone, and thank you for all your help in advance. I currently have hot water radiators. One zone for the entire house. I want to convert to hydronic. 2 zones one for the 1st floor and 1 for the second. I plan on using a taco 4 way mixing valve with boiler protection and outdoor reset. i have calculated my heat loss to about 32000. I plan to have2 manifolds, one for each floor. 3 loops with 1/2" o2 barrier pex on both manifolds. My loops will be less than 300 feet. The part im having trouble figuring out is how to layout the pex loops. On the first floor i plan to put tile in the kitchen, bathroom, and pantry, ill be doing a mud job to run the pex through. On the second floor will be a "staple up" application under the Bathroom only. Everything else is going to be carpeting. I have read not to run the pex to close to toilets, cause of the wax ring, or under the shower and cabinets. I also wasnt sure what size piping for the near boiler piping, if i had to guess i would think 3/4.

Steamhead

"Hot Water" and "Hydronic" are the same thing.

JUGHNE

If you have cast iron radiators and need most of the heat they put out, then IMO you will need a lot of pex to replace that heat.

Jamie Hall

I think that @DiyEverything is confusing the term hydronic -- which applies to all forms of heating involving heat transfer with water -- and radiant. Sounds like they mean radiant. And I agree with @JUGHNE -- they need to do their heat loss numbers very carefully, as if that is the case they may find that they simply can't hit the required heat delivery Particularly if there is carpeting involved...

RomanP

I wouldn’t lay pex more than 12” on center. Please make sure your carpeting is pretty thin( Think of having thick carpet over radiant equal to having insulation over it). For 32000 BTU heat load, 3/4” is sufficient. At delta T of 20 degrees, you can have up to 4 GPMs running through your 3/4” pipe, which is equal to 40000 BTUs. In ideal world, to get a maximum bang for the buck, I’d recommend using a little high efficiency boiler to maximize that efficiency, but it does have upfront cost.

Good luck with your project

DiyEverything

Thank you everyone for the speedy replies. I believe i am confusing the terms hydronic. I read somewhere that radiant meant electric and hydronic meant water.
I was planning on running my pex loops 8 inches on center, with aluminum heat transfer plates.
Is there a specific layout to run the pex? I have looked at many pictures from google. Some focus on having the beginning of the run along the outside walls, and some stress that there should be the feed next to the return to ensure even heat distribution, without hot or cold spots. How important is it that it is 100%perfect?

JUGHNE

There are other patterns to consider if a room has 2 outside walls.

Bathroom floor area limit how much tubing you can install.
We put plates/tubing in the wall above the tub, the skirt of the tub and an inside corner in the bath room. Under floor was added years later for just the warm feet feel. What was added would not have heated the bathroom by itself.

It is only a matter of removing sheetrock.
Replacement of SR is simpler if you cut the rock horizontally 6" or so below the ceiling top inside corner. Same with preserving any outside corners with beads.

newagedawn

if got the basic terms confused, do you know what type of pex to use? radiators are awesome, why you want to get rid of them?

DiyEverything

Thank you everyone for the speedy replies. I believe i am confusing the terms hydronic. I read somewhere that radiant meant electric and hydronic meant water.
I was planning on running my pex loops 8 inches on center, with aluminum heat transfer plates.
Is there a specific layout to run the pex? I have looked at many pictures from google. Some focus on having the beginning of the run along the outside walls, and some stress that there should be the feed next to the return to ensure even heat distribution, without hot or cold spots. How important is it that it is 100%perfect?

DiyEverything

Hello, i want to get rid of them cause there always in the way of furniture. I was also under the impression that radiant was more energy efficient. Also i get temperature swings, the 1st floor will be 72, while the 2nd is 78. right now it is 1 zone. I also would like the warm foot feeling.

I planned to use oxygen barrier 1/2 inch. I found some on amazon at a good price, that states that its for heating.

None of the showers or tubs will be on the outside wall. How far up the wall would the pex run. Is there a web site or pic i can look at for reference? Im gutting the 1st floor bathroom and kitchen down to the beams, so now is the time to do everything. How ever on the second floor ill only have access to the bathroom from underneath. So i can run the pex anywhere except around the toilet due to the wax ring. I do plan to insulate, as it will be a staple up installation, i was planning on using 2 inch foam board.
How close in feet do the loops on one manifold need to be if they have balancing valves on them?

Jamie Hall

DiyEverything said:

Hello, i want to get rid of them cause there always in the way of furniture. I was also under the impression that radiant was more energy efficient. Also i get temperature swings, the 1st floor will be 72, while the 2nd is 78. right now it is 1 zone. I also would like the warm foot feeling. ...

How close in feet do the loops on one manifold need to be if they have balancing valves on them?

On more energy efficient? Nope. Nor is it less. The energy efficiency is controlled by the relative envelope -- building -- tightness and the efficiency with which the heat source -- boiler or power plant -- converts fuel to heat. How you get that heat into the building from there has very little to do with it, although the adequacy of the controls may have a lot of influence.

On the temperature swings -- again, that's a control problem, not a heat source problem. Switching to radiant won't help that a bit; making multiple zones of your present system, with proper controls, would.

I'll agree with the warm foot feeling. It is nice. But to tear out an existing system which works, although perhaps with poor controls, to put in a whole new system for that? Um...

On the close in feet question -- it's not just the length in feet. The number of bends in the layout and the number and type of other fittings factor in

JUGHNE

You mentioned the kitchen, bath, pantry and 2nd floor bath.
What will heat the rest of the house?

Where are you located as far as design degree day temp?
How old is your house?

DiyEverything

I wasn't planning on replacing the system, i was going to install a mixing valve. The taco 4 way r series mixing valve, it provides boiler protection and outdoor reset.

DiyEverything

The house is built in 1920, but the second floor has spray foam insulation, and most of the first floor does as well. so the house will be sealed very well and insulated. Im in new york. i want to convert the entire house to radiant. Using the same boiler, its very new, a couple years old. using a mixing valve to bring the temp down. i would like to have 2 zones, 1 for the 1st floor and one for the 2nd floor.

Danny Scully

Where in New York @DiyEverything?

DiyEverything

Staten island.

leonz

You should have a heat study done, have the boiler serviced and perhaps have the hot water radiators flushed out and cleaned.
A flat panel hot water radiator would work in the bathroom along with a hot water heated towel bar.

Hot water radiators are very efficient and as you have them already I would not rip them out as they have been working for you. It may be worth your while to see about installing blue board insulation behind each radiator to reduce the heat loss to the exterior wallboard if you have the room behind the radiator.