Expansion tank location and air separator w/ Make up location

STONECREEKSERVICES

 Any problem with locating air vent w make up and expansion tank in primary loop in mod con boiler?  The secondary circulator is right at the closely spanned tee. Both circs run full time when call for heat. 

GGross

Whichever loop has the expansion tank is the primary loop, so the expansion tank is always located in the primary loop. Draw what you are proposing please

EdTheHeaterMan

The system loop is what you mean to say. (@GGross is right) That is the best location for the expansion tank for most applications. the boiler loop is OK but it makes it difficult to pump away and have the air vent at the hottest point in the system. That is because the ModCon boilers usually have a rather restrictive heat exchanger, so they want the boiler circulator on the return in order to ADD pressure to the boiler

To have the system as air free as possible, you want the lowest pressure and the highest temperature in the same location. This is where you will place the air separation/vent device. and if you put the auto feed and the expansion tank on the hottest pipe and pump away from the expansion tank, you will be using Physics to your advantage.



There is a complete explanation of why the Physics of Water makes this the best design in a book called. Pumping Away available in the store on this site or on Amazon.com

STONECREEKSERVICES

Trying to post a diagram. Not sure why won’t let me. In your diagram Ed the air eliminator and exp tank w make up are located at drain valve and purge point before highest temp red info before the tee. The system supply circulator is right next to that tee. Thanks for the help. Will keep trying to post pic

GGross

STONECREEKSERVICES said:

Trying to post a diagram. Not sure why won’t let me. In your diagram Ed the air eliminator and exp tank w make up are located at drain valve and purge point before highest temp red info before the tee. The system supply circulator is right next to that tee. Thanks for the help. Will keep trying to post pic

If you have it in a jpg or png format (i'm sure other formats work as well) you should just be able to drag and drop it into the comment box. Not sure how it works on mobile

STONECREEKSERVICES

STONECREEKSERVICES

STONECREEKSERVICES

STONECREEKSERVICES

Evolution of heating😎

EdTheHeaterMan

I like the old coal boiler. I guess that is gone now, but it looks like it was well kept.

As a result of the circulator location, the Extrol tank/auto feed in this location is acceptable. That PONPC actually translates to making the low pressure of the system pump still pumping away from the PONPC. That will cause air in the radiators to be absorbed and released at the boiler output where the hottest water is. Although not the best location, it is about as good as you can get based on the circumstances. You should be fine. But you now are using the boiler loop as the primary and the system as the secondary. not that there's anything wrong with that. It's just semantics.

This is a rework of your system, the actual pipe lengths are not accurate but the component relationship is correct.