Confused about piping!

JohnLappe

I am installing a Williamson Freestyle boiler to replace a Munchkin and am trying to pipe it properly. The system is piped Primary/ Secondary and has 1 zone . radiant heat in the floor, below the boiler. As it is piped now, the expansion tank/ air separator/ fill is piped in the return just before the pump about 6" from the boiler, Reading the book Primary-Secondary Pumping Made Easy!, by Dan Holohan I know that the existing piping is wrong. I looked at the piping drawing in the install manual and it seems wrong also any suggestions on the Correct piping I am adding 2 pictures to hopefully clarify, a pic of the existing installation and a copy of the install diagram.

hot_rod

You might consider a hydroseparator instead of P/S piping.

The sep assures proper separation regardless of the pumps, give you excellent dirt, air, magnetic and hydraulic separation.

It cleans up the piping and saves hours of labor.

Zman

Your new boiler has a heat exchanger which is very similar to the munchkin you have now.
I believe that the manufacture prefers pumping into the boiler because of it's high head loss characteristics. By pumping into the boiler, the water in the exchanger is under higher pressure, reducing the likelyhood that could flash to steam under extreme conditions.
I don't have any major concerns with your present installation or the drawing you posted. It would be nice to have more straight pipe on either side of the closely spaced tees, but overall it should work just fine.
You should also rotate the circ in the picture 90 degrees so the shaft is horizontal not vertical.

JohnLappe

Thanks for the responses, I guess my biggest issue now is that the replacement boilers piping connections are on the bottom , so it seems that if I am to pipe it the way the manufacture suggests, I will end up having the supply side of the secondary having to first fo up above the boiler then back down to the floor.

Zman

Can you just lower all of it? You could clean up the hydro separation while you are at it..

JohnLappe

Boiler must be mounted high on the wall to keep it out of the way of people and workbenches.

Gordy

That's a service nightmare off a ladder.

Zman

Ok,
So why don't you hang the new boiler where the old one is and pipe to it? The manufactures drawing is essentially the same as what you have. The slight location difference of the expansion is not a big deal.

JohnLappe

one other wrinkle, the existing install doesn't have a LWCO, I guess they relied on the water pressure switch, I was going to install one just above the boiler, in the supply line, is this acceptable?

JohnLappe

here is a quick sketch of how I think I can pipe the system

hot_rod

All that to accommodate a LWC?

Does your code require a LWC? Most boilers now have a low pressure switch as a safety and also shut down if the delta T rises quickly, or high temperature caused by no flow, and a high limit cutoff. So at least 3 safeties are already on board.

Some of the tube type HX boilers have extra ports on the boiler itself, maybe add a probe type LWC there?

Drop out the bottom, use a vertical air separator and eliminate all the round about.

JohnLappe

Thanks for all the suggestions, I have some good ideas to use but it appears that I will pipe as I sketched due to the fact that Code does require a LWCO and there are no provisions in the Williamson Freestyle boiler. I really wish I could avoid the LWCO but, must comply with code.