Radiator feed and return on same side (feed on top) (return on bottom)

pjohn1993

Looking for some insight on the matter of efficiency, I took about 15 old cast iron rads out of an old house in asbury park a few towns over, they were all ran out of the same side(feed in the left top side, return out the bottom left side) so when renovating my basement I ran the lines according to them. now we are all sheet rocked and spray foamed and im learning the best way to run is bottom to bottom .how much efficiency am I losing using the same method the were originally set up? should I feed the top left then run the bottom return around to right side behind it for better results (diagonally from top left(feed) and bottom right (return)?

another question-

my boiler feeds a 3/4 line then I reduced it to he oxygen barrier 1/2 per then tees off to feed each radiator, in my case only 2 rads per zone

. then 1/2 pex returns both tee together but before returning to hot water heater it jumps back up to 3/4. I know you can size down while feeding but what about sizing up when returning ? I am by no means a professional but it seemed like a simple set up and im learning a lot as i go . please any insight on the matter would be great , I'll post some photos of what I mean on the return lines, im hoping the way I set it up it won't restrict returning water form rads - thanks !

pjohn1993

to clarify its a tankless hot water heater navien system not a boiler.

EBEBRATT-Ed

I would feed them the way they were originally fed or diagonally. I would not go bottom bottom. The pipe size you need is dependent on the size of the heat output you need for the room. Have you done a heat loss?

Intplm.

It doesn't sound like you have done a heat loss calculation as @EBEBRATT-Ed asks above.
Doing a heat loss calculation is your first step. Anything else done before that can have you working in circles.

pjohn1993

Heat loss is very minimal, one door, one fire rated door(to garage) on one zone , all spray formed and less then 150 sqft, with two oversized 8.5"wide 33" L radiators, (tucked in nooks) its an entry hallway/garage , also have the zone ran on a thermostat so wondering what kind of valves should be used on flow and return areas of radiators. Zone 2 is approx 300 sqft with two more the same size radiators with radiant heat above on next floor , (likely won't supplement heat but should help a bit , everything is spray foamed , including rim board above overhead, with one French door , new construction, caulked sealed, foamed around jams of doors all spray foamed.

My question is, is it worth running the piping, which will be visible, to the regualar ports of bottom left to bottom right , or keep it clean and route it directly off wall to flow in top of left side , return from both of left side how I originally ran it to fit existing radiators.
thank your for your time and input -Pete

pjohn1993

EBEBRATT-Ed said:

I would feed them the way they were originally fed or diagonally. I would not go bottom bottom. The pipe size you need is dependent on the size of the heat output you need for the room. Have you done a heat loss?

yes they were originally fed top left feed, then return at the bottom left . That's why I ran the pex the way I did to begin with , shouldn't have jumped the gun on the design im thinking . I woudent mind routing the pipe to the standard bottom left to bottom right , may have an industrial look I just want to make sure the system runs efficantly. also curious if 1/2 he pex will do the job with these big a** radiators lol ?\! thanks again for your imput its highly appreciated ,im a carpenter not a plumber !

pjohn1993

Intplm. said:

It doesn't sound like you have done a heat loss calculation as @EBEBRATT-Ed asks above.
Doing a heat loss calculation is your first step. Anything else done before that can have you working in circles.

I did radiant heat on the floor above and had a company calc out and do heat loss for me , (radiant tec) never hired them or paid but used there calculations via email ) such a small area downstairs I am most defiantly overkilling the space, just trying to get the system working the best way possible, I I can run them traditionally but would have to remove the gaskets and refit them to run bottom to bottom , they are set to run top left feed and bottom left return for some odd reason . wounding mind doing that just seeing if its worth it , when im already overkilling , if I lose 5 % efficancy so be it , not worth spending the time and money for more pipe to run them bottom to bottom , thank you for your time

pjohn1993

pjohn1993 said:

EBEBRATT-Ed said:

I would feed them the way they were originally fed or diagonally. I would not go bottom bottom. The pipe size you need is dependent on the size of the heat output you need for the room. Have you done a heat loss?

yes they were originally fed top left feed, then return at the bottom left . That's why I ran the pex the way I did to begin with , shouldn't have jumped the gun on the design im thinking . I woudent mind routing the pipe to the standard bottom left to bottom right , may have an industrial look I just want to make sure the system runs efficantly. also curious if 1/2 he pex will do the job with these big a** radiators lol ?\! thanks again for your imput its highly appreciated ,im a carpenter not a plumber !

yes I think ill do top left feed to bottom right return and run the pipe behind radiator hidden so I have a diagonal feed and return I've heard from other forums its best but debatable . only because I see all standard rads ran bottom to bottom

pjohn1993

any imputt on jumping from 1/2 pex to 3/4 on the returns ? do I need balancing valves ? not so sure about the set up on the returns !im in New Jersey and we do see some below freezing temps for weeks on end , sir making sure 1/2 pex will handle the job with such large rads (8.5"w33"L)

Rich_49

You're fine with the 1/2 pex . with what you've described 1 gpm will be more than adequate to heat the space . You should always do a heat loss though and NEVER again consult with Radiant Reck .

pjohn1993

Rich_49 said:

You're fine with the 1/2 pex . with what you've described 1 gpm will be more than adequate to heat the space . You should always do a heat loss though and NEVER again consult with Radiant Reck .

I have heard a few horror stories on this forum, radiant reck lol thats good ! , thank you Rich, from your experience, is it worth changing the radiator feed and return to bottom bottom ? or keep them as they were originally ran, top left feed and bottom left return . how much am I really losing to have to re fit the rads , thanks again! cheers

Steamhead

That piping arrangement should work fine, as long as the hot water enters at the top and the return comes out the bottom.

pjohn1993

what kind of valves are required on flow and return if the room already has a thermostat communication with the zone feed ?

pjohn1993

Steamhead said:

That piping arrangement should work fine, as long as the hot water enters at the top and the return comes out the bottom.

what kind of valves would you recommend on the feed and supply with this configuration if the room is already on its own thermostat communication with the zone, thank you