Cast Iron Radiators With Manifold and Pex Home Run

 
Salemcoal
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Post by Salemcoal » Mon. Mar. 10, 2014 5:32 pm

Again , thanks to those who offer practical advice based on experience of running the pex with a home run system with cast iron radiators. Would appreciate it if the thread wasn't hijacked .

 
Scottaw
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Post by Scottaw » Mon. Mar. 10, 2014 9:54 pm

It's absolutely do-able. High quality oxygen barrier pex is a must. I used pexsupply for my potable water job, they have tons of info there for system design and install. You will probably
Want to stub out to the rads in copper, just for appearance.

With a manifold system I wouldn't bother with balancing valves, you can turn off individual rads and add them later if necessary.

The beauty of a manifold is complete user control over each appliance. You could turn off individual rads in shoulder seasons, or even turn off all the rads and leave your DHW running in the summer.

We want lots of pics if the install.

 
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Sting
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Post by Sting » Tue. Mar. 11, 2014 10:04 am

SAM COAL;

Advice from the public internet is free- Normally advice is worth what you pay for it - around here you will [normally] find very hi quality advice - fast service - and great directions = all for FREE

Whats that worth?

Nothing????
Everything???

It Depends!

Now that written - you may also have to put up with a little of the banter that takes place - Deal with it!

so back to your first post in this thread -see I found it just a little too "open ended"
I would like to see a question that could actually be answered on these pages because as a figment of the public internet, I am not standing in your boiler room to be able to cast dispersions or lambast praise!

What EXACTLY do you need??? *Are you looking for design assistance? * Are you having trouble with an existing retro fit? *Do you want to do this your self? * Do you know what end of the pipe wrench to hold? * Are you looking to Hire? *Do you need to reinvent the wheel?
have you looked in all these threads and found the books that are recommended to get you up to speed so you have the knowledge necessary to not get screwed by the lowest bidder? * or even know what we are chatting about?

Kind Regards
Sting

 
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Post by kstills » Tue. Mar. 11, 2014 10:09 am

Scottaw wrote:It's absolutely do-able. High quality oxygen barrier pex is a must. I used pexsupply for my potable water job, they have tons of info there for system design and install. You will probably
Want to stub out to the rads in copper, just for appearance.

With a manifold system I wouldn't bother with balancing valves, you can turn off individual rads and add them later if necessary.

The beauty of a manifold is complete user control over each appliance. You could turn off individual rads in shoulder seasons, or even turn off all the rads and leave your DHW running in the summer.

We want lots of pics if the install.
I'm not sure I agree with this, however I don't have a manifold, just several CI rads of different sizes.

I don't think you can balance the system well unless you either install the valves or separate the circuits with their own circulator. My experience, with two zones and different sized radiators, is that the rads that are the same size all work as they should (upstairs) while the rads that are completely mismatched have major balancing issues (downstairs). I plumbed a reverse/return system using pex, two zones with a separate circulator for each. It works much better than the prior single zone system, but it's not optimal by any means.


 
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Sting
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Post by Sting » Tue. Mar. 11, 2014 10:14 am

kstills wrote:
I'm not sure I agree with this, however I don't have a manifold, just several CI rads of different sizes.

I don't think you can balance the system well unless you either install the valves or separate the circuits with their own circulator. My experience, with two zones and different sized radiators, is that the rads that are the same size all work as they should (upstairs) while the rads that are completely mismatched have major balancing issues (downstairs). I plumbed a reverse/return system using pex, two zones with a separate circulator for each. It works much better than the prior single zone system, but it's not optimal by any means.
Image

 
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Post by Sunny Boy » Wed. Mar. 12, 2014 7:50 am

If you can afford the valves, they are cheaper then circulators and thermostats and you can balance the zones.

When I built the radiant heat floor system in my shop, I used valves for each zone in the 5 zone manifold. It has worked very well, and it's very easy to adjust and balance for each room and area's needs. Just involves a bit more, time-wise, to adjust then a thermostat, but saves a lot of money. And they add the advantage of being able to isolate each zone while not completely shutting down the heating system, if the need ever arises to open that zone for repairs.

For instance, I run the temp higher in the paint booth to help compensate for exhaust fan heat-loss during painting. Makes for a faster heat recovery.

In the mechanical bays I don't need the temp as high - especially if I'm laying on the floor working under a car.

And I run the heat a bit higher in the loop near the entrance doors - again, faster recovery if there's a lot of going in and out the shop doors.

And I can change any one of those zones with the simple twist of a valve.

I had thought about just one valve per zone at the feed manifold, but for a bit extra cost, I installed valves for each zone at the return manifold too. As I mentioned above, with the bitter cold winters we get here, I liked the idea of being able to work on a zone without having to completely shut the system down.

Just remember not to shut off too much, or you'll need a by-pass loop to take the strain off the circulator.

Paul

 
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Sting
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Post by Sting » Wed. Mar. 12, 2014 8:01 am

A bypass loop is more important for boiler protection than it is for circulation issues. It can cause more circulation issues than it fixes [if] it not installed correctly ---- but then so many examples in these threads reflect that.

but back to that loop

Circulators will draw less amps when you choke the flow on the load side - never choke the flow on the suction side because that will make the pump work to capacity and possibly draw air in past the seal and into the system

Here is another analogy - take your shop vac - turn it on - listen to the motor - plug the suction hose - What happens?????

The motor speeds up -- why? It isn't going into warp drive! It isn't trying to draw more air that it cannot! There is no "microprocessor that tells it to "STEP ON THE GAS' We need more power Scottie".... The vac motor fan is simply spinning in the air that is trapped in its fan cavity and since that air is not moving the motor is under almost NO LOAD!

Same with a circulator - if you choke the flow on the load side it is moving less energy bearing liquid and that equates to it is working less and [possibly] drawing less amps
Last edited by Sting on Wed. Mar. 12, 2014 8:11 am, edited 1 time in total.

 
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Sting
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Post by Sting » Wed. Mar. 12, 2014 8:07 am

Since no one it hitting the target I set up earlier ....

Let me post that I was looking for someone to suggest temperature reducing loops to control the various radiation needs.

Such as above where SunnyBoy runs the load cooler in the work area - but higher near the door where a faster recovery is needed.

Yes choking valves can produce a similar effect but balance and operation [while functional] is not optimum.

READ the books folks!


 
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Sunny Boy
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Post by Sunny Boy » Wed. Mar. 12, 2014 8:25 am

I had heard similar from all the suppliers that wanted me to install expensive valving an fittings, etc. Turns out they were going by what their book said, but not one of them had ever built or worked on a radiant heat system. So, at the recommendation of a friend that owned a large oil company, I called the Hydronics Institute in NJ.

The head of the radiant heat floor division at the Hydronics Institute said that simple choking valves will work as long as I had ample zone capacity. He copied sections of his books on simple radiant heat systems and sent them to me. Using that info is what I built the system from. It's a simpler, less expensive, zoned system then what the two plumbing supply house wanted me to install, based on their books from the manufactures. And it works very well.

I should have clarified. The bypass loop was not for full-time use. He also recommended a bypass loop that could be turned on, or off as needed, if I was setting up with fewer zones, but with the five zones, I didn't need it the few times I've turned off up to two of the five zones.

What the manufactures and the books said may well be fine, but with 20 years experience of that system in my shop, I know the choking valves on manifolds work very well also.

Sometimes the books, or some books, don't tell all.

Paul

 
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Sting
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Post by Sting » Wed. Mar. 12, 2014 8:44 am

Sunny Boy wrote:simple choking valves will work as long as I had ample zone capacity

Paul
YOU are exactly correct and a staunch testimony to "It Depends"

very sorry if you took offense to my advice to read the books

it was not directed at you - it is directed at the folks that wish to "reinvent the wheel" when it is not necessary

 
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Sunny Boy
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Post by Sunny Boy » Wed. Mar. 12, 2014 9:31 am

Sting wrote:
Sunny Boy wrote:simple choking valves will work as long as I had ample zone capacity

Paul
YOU are exactly correct and a staunch testimony to "It Depends"

very sorry if you took offense to my advice to read the books

it was not directed at you - it is directed at the folks that wish to "reinvent the wheel" when it is not necessary
No harm - no foul. ;)

And I can understand where your coming from. More than half my business is, literally, having to redo a lot of "reinvented wheels", . . . and carburetors, . . and distributors, . . .
:D
Paul

 
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Post by Salemcoal » Sat. Mar. 15, 2014 9:44 pm

Are you saying my system should be set up pumping away (from supply) so the circulator is not choked out?

 
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Post by DePippo79 » Sun. Mar. 16, 2014 3:49 am

"Pumping Away" by Dan Holohan. Having the circulator on the supply side will pretty much make your system self bleeding. Short answer. Matt

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