Radiant Floor - Manifold Relocation

pberger

We are starting to look at replacing our old electric boiler with a newer, efficient, gas model to supply our radiant floor heating. The system works fine but our hydro costs are “through the roof”. I'm being told, by the experts, that the manifolds must remain in the ceiling due to the requirement to bleed off any air locks that may occur from time to time. Air naturally rises in the low velocity system, I'm being told, so they should be placed high relative to the boiler and close to the floor, heating lines.

Since we’re replacing the boiler, I'd like to move the manifolds down into the utility room, about 5 feet lower, out in the open, so that the lines can be adjusted to suit each floor heating zone and to make them available for service if need be. So the question is is there a way to bleed the air out of the system if the manifolds are placed low (in the utility room near the boiler) relative to the actual floor heating lines above in the ceiling? Having those manifolds jammed up in the ceiling between the floor joists, seems like such a pain. The install was performed 17 years ago and I’m not even sure if the manifold themselves are self-bleeding - I guess I should check.

Your thoughts would be appreciated.

Zman

You can usually move a manifold without issues. A picture would be helpful.

pberger

Here are a few pictures of what I'm referring to:

Zman

It looks like it would be a bit time consuming to move the manifold. I do see why you would want to move it for serviceability.
As far as air elimination goes, I don't see an issue with moving the manifold. Your existing boiler is piped incorrectly as it has the circulator pumping towards the expansion tank rather than away from the expansion tank.
The poor fellow that installed it probably does not understand how this orientation effects air elimination (negatively) and thinks that putting the manifold higher is the solution.
I would suggest asking the new installer to either pipe the new boiler per manufactures instruction or post the drawing here for review.

hot_rod

sure you can move the manifold. It looks like the end cap with the air vents can be rotated so the manifold ports would face up, air vents vertical. Some brands offer inverted manifolds for piping up.

It would be nice to move it down a bit without needing to extend the loops with couplings.

Label all the lines when you remove them.

Dave H_2

Location of the manifold is a function of location to the rooms served, zoning ease, wiring and service, not for air elimination.

However, it should NOT be placed for the sheer removal of air. Yes they have air vents built in, that is just for ease and convenience, but use an Air Eliminator for that purpose. Place the manifold wherever you like. Maintain the proper pressure in the hydronic system but use a good air elimination device.

Dave H.

hot_rod

It looks like the circulator is pumping into the return of the boiler, and maybe an air scoop is just out of the picture above the expansion tank? Maybe take a larger view shot.

Ideally the circ pump should pump away from the expansion tank, central air purger on the hot out from the boiler.

Not sure what the 1/2 cross over pipe with ball valve is about?

pberger

Here are two more pictures, for your review. Thanks for your help so far.

hot_rod

Sounds like a re-pipe with a new boiler is in the plan? Here is an example of the components and locations for a typical cast iron type boiler, single temperature system.

I don't see an air purger on your current system, a good micro bubble type of air purger should be included and properly installed on the new upgrade.

pberger

Yes, a new propane fired boiler is in the plan - IBC HC13-50 NG. The system is a 4 zone system, into cement, on a slab on grade floor and I'd like to move the silly joist mounted manifolds downward into the utility room, plumb the system properly, and clean up the mess I have.

If I pull the manifolds down off the ceiling what else do I need to be aware of? You mentioned an air purger, anything else?

Thank you for your diagram and input. This is helpful.

Gordy

As far as the manifolds verses air , and their location. Total B.S.

I had radiant ceilings from the 50's the only purge point were the bleeders in the manifolds in the basement of a ranch style home. I can tell you that air will find its way back to an air removal device. That is with proper purging, and proper flow rates above 2 fps.

Hilly

@hot rod The I/O manual is probably part to blame for this installation. It's unfortunate. I'd say a plumber who wasn't hydronic savvy installed this and figured they would just do it by the book and all would be okay. Just my guess, but I recognized that installed since there's 1000's of those around these parts. They did omit the air vent at the top of the boiler though. There's an internal baffle and 1/2" tapping for an AAV, it comes plugged and is under the i/o manual there. Think the manuals says that or an external air eliminator can be used.

hot_rod

Hilly said:

@hot rod The I/O manual is probably part to blame for this installation. It's unfortunate. I'd say a plumber who wasn't hydronic savvy installed this and figured they would just do it by the book and all would be okay. Just my guess, but I recognized that installed since there's 1000's of those around these parts. They did omit the air vent at the top of the boiler though. There's an internal baffle and 1/2" tapping for an AAV, it comes plugged and is under the i/o manual there. Think the manuals says that or an external air eliminator can be used.

Usually that air vent for the top of the boiler is included in the box as is the relief valve. Flow switches are not typically shipped with the boiler.

The boiler would be a good air removal device with an air vent installed, not as efficient as a micro bubble device however.

Hilly

Says it's a 1/2" tapping for air removal while air device and bushing are to be field supplied. I've always put them in with a quality AS anyway, but the majority around here don't.

pberger

For the neophyte can you be clear on the best way to vent out the air from said system - micro device or an air vent? And that said what additional field supplied devices do I require, in your view, to make this a good install?

So then am I OK with placing the manifolds down out of the ceiling near the boiler in the utility room?

Thanks.

hot_rod

Here is the options I would recommend.

A microbubble device removes entrained and dissolved air, the older technology air scoops are not adequate for that.

Better yet, a combo device that can eliminate all air, dirt to 5 micron size, and magnetic band to pull any magnetite particles.

Magnetic seperation is critical if you plan on using ECM type of circulators.