Need some input or help with completing this heating project.

medic6863

I am going to do a repipe of my radiators.
Its sort of what is in the drawing i attached.
The supply will go i to the manifolds and pex al pex will run to each radiator. 2 zones. The circulators will be on the return line.

Questions.

Where should i put the expansion tank?

Anything else should be added in there and where?

Thank you so much. If possible draw on pic and send

Jamie Hall

It would be much better with the circulators on the supply lines, pumping into the supply manifold. Then you could put the expansion tank on the outlet from the boiler, along with the pressure reducing valve. Much better pressure control.

leonz

Jamie is right about this as you need to be pumping away from the boiler to enable better air removal.

Lines crossing each other should be drawn as a hoop/large upside down U crossing the other pipe to avoid indicating a cross connection.

If you follow Mr. Holohans drawings in PUMPING AWAY you can build a pump module.


Why do you wish to repipe your radiators if you have the benefit of all the thermal mass they provide?

EdTheHeaterMan

This explains why you should put the pump on the hot supply pipe, pumping away from the expansion tank. There is a lot of history about pumps and a picture of President Kennedy leading up to the important stuff at minute 22. If you are like Sergeant Joe Friday and want "JUST THE FACTS", start at minute 22. This explains the science of the water in the system.
https://www.youtube.com/watch?v=awxeWBxC4Aw&t=940s.

Intplm.

@medic6863
The Pumping Away book is great. Do look into it.
Here is a drawing that is the best practice.
Where it says gate valve, use ball valves. Where it says fill valve use an auto-fill valve, and where it says air separator use a micro-bubble air separator like a Spyrovent or equivalent.

Intplm.

Intplm. said:

@medic6863
The Pumping Away book is great. Do look into it.
Here is a drawing that is the best practice.
Where it says gate valve, use ball valves. Where it says fill valve use an auto-fill valve, and where it says air separator use a micro-bubble air separator like a Spyrovent or equivalent.

And....one other thing that's not on the drawing. A manual purge on each of the two returns. That's one purge for each returning zone.

EdTheHeaterMan

Intplm. said:

And....one other thing that's not on the drawing. A manual purge on each of the two returns. That's one purge for each returning zone.

Have you ever used one common purge valve for all the zones? This is an idea that I learned from one of @DanHolohan seminars I took many, many, many, years ago
Diagram from Slide A shows a tee at the top of the supply pipe off the boiler.on one side of the tee is a 3/4" boiler drain valve, on the other side of the tee is a full port valve. Following that is the air eliminator expansion tank and the water feed like with all the necessary parts. Following that is the circulator pump. then the supply branches off into 3 different zones or loops of baseboard radiator. At the return of the boiler where the 3 loops come together to return to the boiler there are 3 isolation valves.

Slide B shows that the full port supply valve is closed and all three isolation valves are closed. If you were to charge that expansion tank with the home's water pressure by lifting the fast fill of the auto-feed, you will also charge all the radiators with that same pressure (let's say 45 PSI or higher) without opening the boiler relief valve, because the boiler is isolated by the 4 valves.

Slide C shows that by connecting a garden hose to the common purge and opening it, when you also open one of the 3 isolation valves you will get a high pressure fast purge of water, to push all the air from the first loop. If you then close that first isolation valve and build up the pressure again, when you open the second isolation valve, you will fast purge that second baseboard loop, and you do not need to move the garden hose.

By following this procedure for every baseboard zone or loop after that, you will be able to high pressure fast purge every zone or loop, without ever changing the garden hose location. And you will save on the cost of multiple purge/drain valves and tee fittings. Also save time on purging all the loops. The only added cost is a Full Port valve on the supply.

I have used this design on every conventional boiler system I've installed since 1985. I remember a particularly difficult job at the Dennisville NJ Post Office. It was at the far end of the former postmasters home. We were there purging air at least 3 times per winter for all the years I have served that location. When they needed a replacement boiler, I had an argument with my newly hired Lead Installer. He was convinced that this piping design was all wrong. ("what could the boss actually know about piping a boiler, that's why they hire me")

He became a believer when we fired up that boiler after one simple purge of 5 different zones (including the problem zone). As soon as the circulator started, the SpiroVent started to expel air. As the water heated and returned hot , more air spurts, and the spurts kept happening even after we packed up the tools and left for the day.

The next day we returned to finish up/clean up the project, and the postmaster indicated it kept spurting out tiny bits or air the rest of the evening. In the morning the system was completely air free, all by itself.

DanHolohan

I’m smiling, Ed. Thanks