What happens if,,,

MarkPFalade

you install two Prestige type boilers in a row and then you do an 80% next, have a brain fart and put the fill/expansion tank/ air sep etc in the boiler return instead of after the boiler and before the pump?  I'm thinking not much really but just thought I'd run it by everybody. System is up and running fine, I didn't realize my mistake till the after the fact, on the way home kind of DOH!! thing.

Mark Eatherton

More splainin' please...

Are the TT's and the 80%er in the same system, or two completely different systems?



If the same system, how are they piped?



If different systems, how are they piped?



If they are completely diffent systems, and you just plain screwed up on the 80%er, it depends on the pump used, and the pressure drop incurred by the system. If it is a low head pump, like a 007, and the pressure drop through the system is relatively low, you are correct, probably no affect.



If it is a high head pump, and there is a substantial pressure drop through the system, when the pump is running, the PRV will see the low pressure condition and will slip some make up water into the system at the beginning of every pump start.



Eventually, system fill pressure will equal pressure relief valve threshold, and the pressure relief valve will relieve itself. If the relief valve termination is parked directly over the floor drain serving the system, it could keep bleeding water undetected for a LONG time, eventually destroying all ferrous components in the system, or causing the heat source to lime up and fail.



This is why I NEVER make a solid make up connection to any system, and why I recommend the use of a low pressure cut off in addition to the code required low water cut off.



So what is it? One in the same, or different systems?



BTW, we ALL do these silly mistakes. It's human nature.



ME

HDE_2

My take

The way I read it is sounds like 3 separate systems installed in a row.

No mention of where the pump is on the cast iron system, but again betting on the supply side so the cast iron vessel serves as the lowest pressure point. Not the best place for the tank/fill air elimination but I would lose sleep over it unless the circ is over-sized or piping is beyond normal.

MarkPFalade

3 different systems.

007 pump on the small CI boiler. So yes the boiler is the lowest pressure point in the system. Not the best set up for air elimination I know. I have no idea what I was thinking other than piping in the two TTs one after the other got me in a groove. I do plan to close the makeup once the system is air free so continual introduction of fresh water over a long period of time should not be an issue.



I always figured you DON'T want to discharge to a hidden spot so that a weeping relief valve will be noticed right away.

Unknown

close the makeup

Are you really sure you want to do that?

MarkPFalade

Absolutely,

I always do.