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Old 01-21-2011, 05:05 PM   #1
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Radiant heat manifold configuration


Hello all,
I am anxiously awaiting the snow to melt and ground to thaw so I can have my outdoor wood boiler installed have a little time on my hands and I'm doing the preliminary planning of my radiant heat system inside the house. I am not a plumber but have a reasonable knowledge of the physics of plumbing. I will have a plumber do all the sweating and pex connectors. I will do the rough in work of running the pex and radiant heat panels. My system will be 5 zones of 1/2" pex loops approx 500 ft each.
Plus a Large style 40 Plate heat exchangers NPT 1 1/4" to tie into my 4 zone hot water oil boiler. I plan to run 1" pex from manifold to heat exchanger.


Now here is my dilemma, the manifold I am interested in is a 5 port manifold with


1" Shut-off valve--(5) 1/2" outlets with flow meter-- air vents (supply)


1" Shut-off valve--(5) 1/2" outlets balancing valves-- air vents(return)


My question is, can I put a 1" tee before the supply and return manifold to feed the heat exchanger with out causing any problems with the water flow of the 1/2 line runs.
Do I need check valves at the tee's or ball vales to regulate flow ?


The main feed from the outdoor wood boiler is 1" O2 barrier PEX and I plan to use O2 barrier PEX for whole system.


Thanks in advance for all comments

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Old 01-22-2011, 02:57 PM   #2
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Radiant heat manifold configuration


Ayuh,... It sounds like it'll work that way, as long as you have a pump in the line coming off the exchanger, as the main boiler pump will be out of the loop, when the exchanger is suppying the heat...

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Old 01-22-2011, 04:00 PM   #3
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Radiant heat manifold configuration


I've done radiant heat systems for 15 years or so and I have a few questions for you. Firstly are you sure you plan to run 500 foot pex loops? The pex manufacturers all recommend no more than 300 feet of 1/2" pex in one loop so that you do not start running cold at the end of the loop. Second you say you are planning to install 5 zones. Do each of the 5 branches coming off of your manifolds represent a zone? Or are there 5 loops for one zone? Third, what is the heat exchanger for? Are you going to add a zone for potable hot water or maybe heat a swimming pool or supplement a forced air furnace? You don't have to use heat exchangers with common piping only for radiant heat, plus the transfer effiency sucks. Put in 100 degress and get 75 or 80 degrees out. Right now it sounds like you are planning a single zone heating system(one thermostat), but you speak of 4 or 5 zones?
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Old 01-22-2011, 04:19 PM   #4
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Radiant heat manifold configuration


Quote:
Third, what is the heat exchanger for?
Ayuh,... Big Red, he's using his owb through the exchanger, 'n not in-common water with the house's boiler/ heating loops, is how I read it....

I just built a 4 zone, but mine pumps from the manifold in a primary/ secondary type set up...
I've got 1 zone that's 600' of tubing, but it splits at the manifolds to 2, 300'ers...
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Old 01-22-2011, 05:22 PM   #5
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Radiant heat manifold configuration


Bondo -- yes the Outdoor Wood Boiler has a circulating pump controlled by a thermostat.
I plan on running the 1" pex off the tee from the manifold to the heat exchanger and back to the return tee and then to the OWB.


Big Red -- Yes that is the run count 500' give or take and pardon my misquote of zone as there is one zone and 4 loops with a future loop.
The thermostat will be on the OWB I will fire it up when ever I need it to take the chill off the house.


( 75' to area. 350' of heat transfer area and 75' return run ) loop 1


( 75' to area. 350' of heat transfer area and 75' return run ) loop 2


( 100' to area. 250' of heat transfer area and 100' return run ) loop 3


( 25' to area. 350' of heat transfer area and 25' return run ) loop 4


Do you recommend that That I run 3x100' parallel runs off a main 1" loop. or can I just tweak the flow control valves for each loop.


To answer your heat exchanger question just as bondo stated it is tied into my main heating unit(oil fired boiler with 4 zones) .


To sum up my expectations, I would like the majority of the BTU's to goto the exchanger to circulate through the the main heating system and the rest to go to the radiant loops, as far as cooling down towards the end of the loops does not really concern me that much. I hope to get the largest delta T from the OWB.
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Old 01-22-2011, 05:24 PM   #6
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Radiant heat manifold configuration


No problem with that Bondo. I've put down as many as 12 loops in a single garage of 1/2" pex going from 1 supply manifold to 1 return manifold and not one loop was over 300 feet. The trick is in laying out the pattern so that no loop is 3-5' longer or shorter than any other.
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Old 01-22-2011, 06:02 PM   #7
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Radiant heat manifold configuration


OK it sounds like you are adding the OWB as a backup/supplement to your house system with the manifolds feeding a new zone. So if I understand you correctly I would suggest putting the OWB and the exchanger on the runs or ends of the TEEs and the supply and return manifolds on the branches of the TEEs and put a circulating pump between the supply manifold and its TEE for your new zone. (The fifth zone) The only problem with this will be that you will have to have the OWB running to heat that 5th zone. Your oil boiler won't heat it unless the circulating pump on the OWB is running and if the OWB isn't fired up and its pump is running you will only chill the manifolds. You could put the TEEs in the lines on the house side of the exchanger and heat that new zone with or without the OWB running and the OWB could then be used to boost your system at your call.
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Old 01-22-2011, 08:01 PM   #8
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Radiant heat manifold configuration


I'm curious, how much does installing a hydronic systems cost for a house 3 levels? I am in Chicago.
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Old 01-23-2011, 09:33 AM   #9
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Radiant heat manifold configuration


There are many variables to that question. What kind of construction is your Home? How old is it? what kind of insulation do you have? Do you have plastic vapor barrier under the drywall on the walls and ceilings? Do you have thermal windows and doors? Do you want any of your floors heated? What kind of floor coverings do you have? Do you want 1 zone heating or three zone heating or individual rooms on their own thermostats? Is there access from under any of the floors for staple up tubing? Is there room in your furnace room for the boiler and associated hydronics equipment? Is your furnace room on an outside wall? These are just some of the questions and/or items that need to be delt with. Also you need to understand that with straight radiant heat you don't have any provision for air conditioning. You could put in a separate A/C system but that just doubles the costs. If you are thinking of converting from scorched air to radiant you could remove the furnace and install a simple air handler in its place leaving the A/C coil and bonnet in place. That way you would have heat and A/C and have the possibility of humidity control as well. If you answer all these questions and have good work skills in plumbing, sheet metal, electrical, and low voltage controls you could put in a workable radiant system, either new or as a retrofit for around 9-11 thousand dollars yourself. Obviously if you want someone else to do it it could be more.
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Old 01-23-2011, 10:34 AM   #10
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Radiant heat manifold configuration


Red Wolf you should put in ball valves anywhere you may have maintenance considerations down stream. Say 1" BV's at the TEE branches going to (and From) the manifolds and a 1" BV after the pump on the supply side manifold. Also 1/2" BV's on each of the 4 or 5 loops at both supply and return manifolds for isolation in case a leak develops in any one loop so you can fix it with out turning down the whole system. One other question- You are running a 50/50 antifreeze mix in the lines out to the OWB, correct? Also try to put your 5 banger manifold closer to your heated areas since your heat loops are soooo long. Like around loop 3 or within 25 feet of it. After about 320 feet @1/2" and a maximum 160 degree F water temp on the supply manifold your loops will be effectively cold at the return ends with 350+ foot loop lengths. Antifreeze and water is harder to pump so you might want to look at a slightly larger pump on your OWB volume wise, not necessarilly speed wise and check the maximum operating temperature for the Pex you use from the OWB to the heat exchanger. With antifreeze in the outdoor system and a standard 30 P.S.I. relief valve you can run your hi limit on the boiler to about 235 degrees safely without popping the relief.
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Old 01-25-2011, 11:23 AM   #11
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Radiant heat manifold configuration


Big-Red ( and everyone else) thanks for all the advice in this thread. Just for ****s and giggles I think I am going to run the first loop (500') and tie it into my oil boiler to see what kind of Delta T I get. I will post when that happens about 2 weeks by the time pex tubing gets here. By the way any preferences on pex clamps.brass or SS I am leaning towards SS cinch clamps myself as I will only have about less then 20 connections.
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Old 01-25-2011, 11:36 AM   #12
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Radiant heat manifold configuration


Quote:
I think I am going to run the first loop (500') and tie it into my oil boiler to see what kind of Delta T I get.
Ayuh,... When all is said, 'n done,...
Will these 4 new loops be tied to the oil boiler, 'n draw heat from the exchanger,..??
Or,..
Are these 4 loops ONLY plumbed to the owb,..??

I can tell ya right now, you Don't want the deltaT too high, as if you run water back to the boilers at Less than about 140,...
You're going to have a massive Condensation issue going on, 'n will probably Rust out the boiler(s) in short order....

That's why I'm running a Primary/ Secondary loop system...
The water going To the pex is mixed down to 150, then the return water is mixed back up to 150 before it gets back to the boiler...

My owb also is running a P/S system... Slightly different, but basically sorta the same...
On it, I have another pump that mixes any water coming back, that's below 145, with Hot water, right off the top of it's jacket...
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Old 01-25-2011, 12:43 PM   #13
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Radiant heat manifold configuration


Bondo
I have an unused zone on my oil burner for future use of a finished bsmt. I am going to tie one of my radiant loops into that TEMPORARY. To see what the temp drop will be and too see what the floor temp reaches also to check for expansion sounds.

The 4 radiant loops will be plumb to the OWB only. But I also wanted to have a 1" pex line from the manifold to the heat exchanger That I had planned for the oil burner . I will post a diagram of what I had in mind.

I will also look into the delta T problem. Right now my boiler Hi Lo is 130 180
I do not play with any settings on my boiler I leave that up to oil guy. I just lurch and watch when he is doing maintenance , he says its not rocket science but rockets and boilers have something in common. They can blow up !
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Old 01-25-2011, 01:03 PM   #14
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Radiant heat manifold configuration


Quote:
he says its not rocket science but rockets and boilers have something in common. They can blow up !
Ayuh,... I'm self-educated over the last 40 years or so, with Burners anyways...
I started messin' with the Hydronics maybe 15 years back or so...
As I noted above, I designed, built, 'n installed my 1st Complete system this last year in my rental house...
I've also designed, built, 'n installed my owb, 'n it's tie-in to my existing oil fired baseboard heating system in this house...
I went with a pressurized system that's directly, hydronically tied from the house to the owb...
No heat exchanger involved....


Btw,... You've gotta try really Really REALLY Hard, to Blow up a boiler...
There's the safety pressure relief valves that work quite Nicely....

When I built the owb, I sealed it full of water, 'n Tested it to over 90psi,...
That's 3Xs it's max working pressure of 30psi(the relief valve setting)
That's also 6Xs it's Normal workin' pressure of 12/ 15psi...

Have you/ Are you considering Storage for the heated water,..??
What sorta owb ya got,..??

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