Need advice. New SIPS construction, Hydronic slab on grade, Mod Con combi or Stand boiler / On DHW

The Steam Whisperer

I do have return temperature protection. Simple bypass piping has been the recommended method of boiler protection in high mass/low temp. systems by every boiler manufacturer I've ever seen since the beginning of time, it seems. Burnham, Weil, Dunkirk, Peerless, etc. At first, I didn't understand how it works, but now see it much more clearly and it does work. Most gravity conversion systems with new boilers I've worked on over the past 25 years don't even use bypass piping, and there tends to be more rust at the end of the heating season in the pan than I like, but they run this way for decades without major problems.

DAVIDSEIDEL

Big thanks to GroundUP. Talked to him quite awhile today.
And rather than continue down my merry path to hell with the homemade insulated box, I am going back to separate boiler in the garage. I worked so hard on that damned thing! Thought it was a really great idea too! Not so much.
David

GroundUp

It was nice talking to you David, thanks for the call. I hope you come up with a good solution soon! Winter is on the way ;-)

hot_rod

The Steam Whisperer said:

I do have return temperature protection. Simple bypass piping has been the recommended method of boiler protection in high mass/low temp. systems by every boiler manufacturer I've ever seen since the beginning of time, it seems. Burnham, Weil, Dunkirk, Peerless, etc. At first, I didn't understand how it works, but now see it much more clearly and it does work. Most gravity conversion systems with new boilers I've worked on over the past 25 years don't even use bypass piping, and there tends to be more rust at the end of the heating season in the pan than I like, but they run this way for decades without major problems.

And boiler manufacturers still show and sometimes ship boilers with circ on the return, purger and expansion on the boiler supply. Yet year after year we deal with chronic air problems here, directly related to that poor practice. At least 3 threads currently.

I'd suggest the bypass piping for pump had more to do with preventing thermal shock than return protection, as that was a more realistic scenario with large piping and high mass rads. A big cold slug of 68F water hitting a 180F block.

Weil learned years ago with the GV to build in return protection as those boilers were applied to low temp high mass systems, a simple Hoffmann 3 way thermostatic first, injection pump in later series.

Same with Burnham Revolution, built in return protection. Lochinvar has return protection built into some of their copper fin boilers now. The Germans use a 140F aquastat to toggle the circuit on and off.

So I'd say the boiler manufacturers understand the importance of effective return protection.

I think a 200 dollar valve eliminates the problem. If you can't sense and respond to that temperature condition you may not have 100% protection.

If your method works, and you have it dialed in, I'd say stick with it.

DAVIDSEIDEL

Well, now I have a plan. Going to go with HTP UFT-80 or Westinghouse WBRUNG080W.
Good turn down ratio, Indirect DHW, cheap enough, and I can put one in the house and one in the shop. The lines between the buildings could still be used in the event one or the other went out.
And.......with duplicate units, maybe troubleshooting later would be easier. I also tried to get a price on an IBC SL 10-85 G3.
Wow, you would think I was trying to build a rocket or something. Called IBC, transferred to some distributor, to some guy at heating company. Absolutely cannot get the bottom line for a price. What the hell? Is it big secret........Oh we have this great boiler. How much is it? Well, ah,,,,

NY_Rob

^ FWIW- even though they're the same exact boiler... no professional will service the Westinghouse WBRUNG080W (because they know it's a web-only boiler).
Not good when it fails on a 2deg sat night!

Stay with the HTP version for your own sanity.

DAVIDSEIDEL

Will do....... and thanks!
David