LWCO and Near Boiler Piping In-Floor Slab

rjm

Here in Mass I believe the code for new installation is; a lwco is needed when any radiation below the boiler, 400kbtu or greater or steam boiler. The latter,more than likely,does not apply. You should check your local & state code just to be sure. But it is good practice to install one anyway.
As for the piping it up and then down. it may not keep the water in the boiler. It may siphon the water right out of the boiler.

John_201

LWCO In In-slab Radiant

I'm a homeowner who has an incorrect installation on a 1950's in-slab system. I am trying to work with the contractor to get the near boiler piping corrected. He is going to install a Taco RMB-1 mixing block to get the boiler temps where they need to be and to modulate the temp to the floor correctly. Through all this hassle I have researched quite a bit both here and on other sites.

He says that a LWCO is not necessary. As the system is currently piped it is sending supply water out through the large pipe instead of sending it immediately to the floor through the manifold. Shouldn't the supply go to the manifold and the return be through the large pipe? It seems that sending the supply through about 15 feet of pipe before it gets to the floor is a waste of heat.

Doesn't good and safe practice call for the LWCO?

Thanks, John

mark o

lwco

lwco are code in pa , also the gas shutoff valve you have that is reused , we are required to change out

tim smith

Here in Seattle

We are required to put lwcos w/ test button and manual reset on boilers, also manual reset limits. Just depends on location. As far as mod mixing, did he include it in your bid? If the boiler can't run down to safet floor temp levels due to boiler protection then he needs something to mix down, could be as simple as and mech. tempering valve or as elaborate as motorized mixing w/ reset or injection w/ reset. All depends on boiler requirement and what he included. I would think at least the thermostatic mix valve would be the least to be done. Tim

kpc_9

why not...

in todays world the extra measure will cover your behind. Especially in a older slab set up... Seems strange anyone would not want that. Does he know how to wire it so it works? Also the Pressure relief valve needs to be repiped ...it is bushed down to 1/2"...that is a no-no. kpc

fatty_2

... i don't see any gas shutoff at all?

John_201

Answers To Your Questions

He has a Taco RMB-1 on order that should be in on Monday and recognizes that he needs a plumber to correct the install. I have found out that code in Indiana is to install per manufacturer instructions. This has to be plumber who has experience with fairly complicated piping not just a wax ring replacer. The Dunkirk manual is very clear that a LWCO is required any time the radiant level is below the boiler.

He has agreed to correctly size the pressure relief valve piping and cut the threads off the end so it can't be capped.

The boiler gas valve is out of view but present.

I think the Taco LWCO LTR with reset is what I will insist on.

One final question. Should the to floor output of the RMB go directly to the manifold next to the boiler in the picture?
Thanks

mikea23

LWCO

LWCO on that gas boiler is very simple if you buy a gaurd dog by Mcnld Miller it has a wire harness that simply plugs into your boiler. Code or not no hydronic system should be without one.

mark o

gas v

the gas bv I was referring to is the repiped one to the water heater.( new teflon tape)

John_201

There is on on the water heater but it can't be seen in the photo. Thanks