large hydraulic separator / LLH options

jcm55

Bought a house this past June with some large heating loads. Snowmelt system for 2300 sqft driveway + 700 sqft 2nd floor deck. And radiant heat for 4000 sqft interior.

I'm planning to replace the 30+ year old boilers with a cascaded pair of Lochinvar Knight 285 Kbtu wall-mount boilers. These have 1.25" supply / return, and Lochinvar recommends 2.5" primary piping for a cascaded pair.

There are lots of reasonably priced options for hydraulic separators with 2" ports, but as soon as you go up to 2.5", the prices seem to skyrocket to $2000+. And they've all got ANSI flanges -- probably another few $hundred on fittings for those.

Any lower-priced options I'm missing? Recommendations on folks who do custom fabrication? I've seen Earth Lee mentioned in some old threads, but looks like they may be out of biz now.

ratio

for a while now I've thought about using Victaulics (or equivalent) & grooved pipe to build up a separator (2" inlet, 1, 1¼, & 1½ outlets on a piece of large vertical pipe), but haven't gotten to the pricing part yet. I can't imagine that it wouldn't work just fine.

psb75

You could use a medium-sized buffer tank with 4, 2" ports to function as an hydraulic separator.

mattmia2

ratio said:

for a while now I've thought about using Victaulics (or equivalent) & grooved pipe to build up a separator (2" inlet, 1, 1¼, & 1½ outlets on a piece of large vertical pipe), but haven't gotten to the pricing part yet. I can't imagine that it wouldn't work just fine.

For a homeowner large copper might be more accessible since it could be joined with a couple large torches. Could also get a shop to weld one up.

EBEBRATT-Ed

Have your local welding shop give you a price. A piece of 6" pipe with welded caps on each end, drain on bottom vent on top with 4 2 1/2" half couplings welded in.

If you find the right guy you may get under your price

hot_rod

What is the flow rate, the larger on either side? Look at the Loch info to see the minimum flow rate and if that delta is acceptable to your design.
There is some fudge room in those sizing numbers. Caleffi speaking, the suggested flow rate it to keep the velocity inside the sep (top to bottom) as low as possible, below 1 fps. Bumping the flow a bit would increase that but not hamper the separation, air or dirt removal function.

The beauty of a good separator is it accomplishes 4 functions, hard to home make one with all the features.

A couple 6X2 crosses, 2 plugs and a 12" nipple between would be another simple to build version.

Zman

How big are your heating loads? With 285 boiler, a buffer tank would be a good plan.

jcm55

hot_rod said:

A couple 6X2 crosses, 2 plugs and a 12" nipple between would be another simple to build version.

I actually thought of this (or very similar) but who makes crosses like that? I poked around online for a while and couldn't find anything that big.

jcm55

EBEBRATT-Ed said:

Have your local welding shop give you a price. A piece of 6" pipe with welded caps on each end, drain on bottom vent on top with 4 2 1/2" half couplings welded in.

If you find the right guy you may get under your price

This is a good call. I'm thinking 6" stainless square tube with ends welded on, and 2.5" nipple for the ports, plus fittings for drain / vent.

If I'm going the custom fab route, do you think it's better to do four 2.5" ports with boilers and load loops combined externally? Or with separate 1.25" ports for the boilers and load loops, like the Bosch-Worcester one below that they sell over in Europe. I'm thinking the separate 1.25" ports might save some money in not having to deal with any 2.5" pipe or fittings.

mattmia2

Each boiler has its own connection, it isolates the boilers. Can just use large steel pipe, the system water will be deaerated so it won't corrode appreciably as long as you keep the system leak free.

Derheatmeister

You could also just use a tee drill on a large diameter pipe with two caps or better yet two bell reducers one for the air vent the other for the Sludge drain..You could also pull some extra tees for the Sensor and even a Magnet..