Routing a 2-pipe reverse return

[Al S]

I am seeking advise on a retrofit of my 1955 ranch that uses 3 tube 6 inch deep convectors of varied length, depending on the room. The design I am considering is a 2-pipe reverse return. The current system is a 1 pipe monoflow that has the 1 inch trunk hung below the joists but is inserted into holes in middle of the basement's steel beam as it takes it circuit around the basement perimeter. I want to take back some of that vertical space and run the trunk and return above the beam into the cavities of the joists, above the beam. The one design challenge (of several) is that when the trunk and return lines take a turn, they have to descend slightly below the joists which are perpendicular to the beam. I am not going to drill into 70 year old 2x8 joists. The entire route will have both trunks (1 inch PEX-B, Oxygen barrier) make its circuit initially above the beam, take the turn and hang about 1/4 inch below the joists and then go above the beam when they two trunks rise again. I realize the routing of 1 inch PEX-B is tough enough. I want to try and minimize 90 degree elbows and use sweeps (I think they're called bend supports). That requires about a 5-9 inch radius. Attaching from a 300 foot spool will be a huge wrestling match bending this pipe without kinking. The use of the elbows introduces a bit more restrictions (18 for supply and return total should I go that route) which would then become a total equivalent length 0f 466.66 feet. The monoflow copper trunk is 123.33 feet total run length. It uses 9 1 inch copper 90 degree elbows It looks like the Grundfos UPS 15-58 FRC can handle that, though it may have to be on speed 3.

All that said, I am then assuming that I need to use air eliminators when the supply trunk is higher (running in the joist cavities). Obviously, where the two 1 inch trunks are suspension clamped near the faces of the joists, there will be a finished soffit on those sections, but a lot less of areas of the basement. I know that it is more desirable to have the trunks on one flat (or monotonic) plane. I'm asking if the use of the air eliminators and where to place them will not cause issues of trapped air. Please let me know if I need to provide further detail to this.

Thanks so very much for any and all help.

-Al

 

[Fitter30]

Why don't you zone the spaces ? Air elimination a micro bubbler style with use of a bladder expansion tank. Plain steel tank won't work with a micro bubbler. Pex doesn't have the same dimensions as copper. Its smaller. 3 tube convector all three tubes single pass ? 9 different heat emitters?

 

[Sponsor]

 

[Fitter30]

Why don't you zone the spaces ? Air elimination a micro bubbler style with use of a bladder expansion tank. Plain steel tank won't work with a micro bubbler. Pex doesn't have the same dimensions as copper. Its smaller. 3 tube convector all three tubes single pass ? 9 different heat emitters?

 

[Al S]

Why don't you zone the spaces ? Air elimination a micro bubbler style with use of a bladder expansion tank. Plain steel tank won't work with a micro bubbler. Pex doesn't have the same dimensions as copper. Its smaller. 3 tube convector all three tubes single pass ? 9 different heat emitters?

Hi and thanks so much for responding. Let me try and unpack this response. Zone the spaces? It is a 1955 single story ranch. The only other interpretation I can make from that is making each emitter a zone? I don't think that's what you mean. There are already air eliminators on the return tank (convectors), return elbow (Slant/Fin H-3 emitter). Expansion tank is at the output of the Burnham ES2-3. All the convectors are of this style here. There are 6 of those convectors and 1 6 foot Slant/Fin baseboard. So, two different styles. The 1 inch copper monoflo feeds 1/2 inch copper risers to the convectors. The baseboard risers were upsized to 3/4 inch PEX-B with an additional monoflo tee at the return.

I appreciate the response, but am no closer to a pipe design going from the "what is" to the "what I want". If I need to explain it better, I am more than happy to do so. I want this to have as many of the "been there, done that" eyes as possible. It has to be in the closest context to what I tried to explain. I may have not explained it well enough though and that's fair.

 

[Fitter30]

Delete

 

[Fitter30]

This company as all types of manuals.

https://www.caleffi.com/sites/default/files/media/external-file/Idronics_12_NA_Hydronic%20fundamentals%20.pdf

 

[Al S]

This company as all types of manuals.

https://www.caleffi.com/sites/default/files/media/external-file/Idronics_12_NA_Hydronic%20fundamentals%20.pdf

Fantastic reference. I'll retain that for sure, thank you. Doesn't address my concerns though for routing a 2-pipe reverse return above a steel beam (within joist bays) and below (across joist faces). I think to be safe, I'll have to add Hy-vent at the points where the pipes run above the beam. I don't think those added tees will create any more head. I also want to minimize the use of 1 inch 90 degree PEX-B elbows and instead use bend supports.

 

[Fitter30]

Fantastic reference. I'll retain that for sure, thank you. Doesn't address my concerns though for routing a 2-pipe reverse return above a steel beam (within joist bays) and below (across joist faces). I think to be safe, I'll have to add Hy-vent at the points where the pipes run above the beam. I don't think those added tees will create any more head. I also want to minimize the use of 1 inch 90 degree PEX-B elbows and instead use bend supports.

With a bladder tank not plain steel tank a micro bubbler will air out of a steel expansion tank. There's you tube videos on them.

 

[Fitter30]

Fantastic reference. I'll retain that for sure, thank you. Doesn't address my concerns though for routing a 2-pipe reverse return above a steel beam (within joist bays) and below (across joist faces). I think to be safe, I'll have to add Hy-vent at the points where the pipes run above the beam. I don't think those added tees will create any more head. I also want to minimize the use of 1 inch 90 degree PEX-B elbows and instead use bend supports.

With a bladder tank not plain steel tank a micro bubbler will remove air out of a steel expansion tank. There's you tube videos on them.

 

[John Gayewski]

Assuming there is no way to route up instead of down which would be better. If you drilled holes in the joists at where they rest on a beam or wall. You could aslo reinforce the beams where you have holes. Assuming your not going to do that... you really only need a tee at each high point that can let the air out during the inital system fill. Over time any air in the system won't be trapped, it will dissolve into the water or mostly be carried away and scrubbed out near the boiler with the mircobubble air seperator. Use an oxygen scavenger in your water to finish the job.