Diverter-Tee Q&A

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Diverter-Tee Q&A

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Bessie

The explanations to questions are very clear and precise. I love this site.

Nadim

very good questions and clear answers

WJLundy

I have a Monoflo hydronic heating system with cast iron baseboard in my house that was built in 1960. It is a 2500 sq/ft sprawling ranch. It is a 2 split system with 1 circulator. It would be a shame to rip out all that 1" and 1 1/4" copper and change to Pex and manifolds. The basement would be a sea of Pex. So, I would like to add 1/2" zone valves in order to zone each room. There would be a total of 13 zone valves. My question: Should the valve go in the supply or the return? There are a pair of Monoflo tees for each zone.

DanHolohan

The zone valve, depending on its pressure drop, might stop flow to the radiator, even when it’s fully opened. Be careful.

chrisp21

I was wondering if someone could help me with an issue I’m having. I have nine radiators on my first floor with a single loop system where every cast iron radiator gets a supply and return meeting back to the main line and that’s one zone. Second zone is my basement with 4 radiators. I have no diverter tees at all just standard pex crimp tees that lead back to main. On my first floor with the 9 radiator zone I have about a 7-10 degree differential on normal 30-40 degree days in ny. We’ve had one below zero degree day and it wasn’t pretty for the heat in the house. First floor is about 1300 square feet. What can I do to even out the heat in my 9 radiator zone without diverter tees if there is a solution?? I saw the system above with spliting the zone in half and increasing the return to a larger pipe size. Would this really help. 3/4” pex is run in my home. Would appreciate any info. Thank you.

Ironman

Water takes the path of least resistance. If there are no diverter Tees to force some of the flow into the branches, then it's not gonna work. There is no solution other than doing it right.

Also, pex crimp fittings are restrictive and should be avoided in hydronic systems. However, Supplyhouse.com does have a diverter Tee in pex.

AnthonyNY

Excellent article. Well put together. Appreciate it.

geoffhazel

why do radiator systems have a loop for each radiator off of the main loop,needing the diverter tees, but baseboard systems are just one big loop per zone with no tees at all?

Solid_Fuel_Man

Because big heavy CI radiators have a lot of water and mass. So if they were all connected in series like copper baseboard the first radiator would get hot and by the time the last one did the room the first one was in would be way too hot.

Using diverter T's helps alleviate this long train and feeds each radiator (almost) equal water temperatures simultaneously.

Baseboard is low mass and low volume so the water travels much faster from the first to the last in the series loop.

Raymo

Good article! I learn a lot from this which lead me to more questions. Don, my house built around 50s and have same setup. One main loop 11/4 in pipe circle around ceiling of my basement. 6 pairs of T (one stander and one monoT with hexagon head) and last pair of loop they used two mono T , I guess used for go up the 3rd floor ---the farthest radiator. And my radiators from 1st to third floors all have shut off ball valves on supply and return ends . My question is how they run the rest of the piping from main to upper floors radiators...in series or parallel ? If they run in parallel do they use mono T like in the main loop does? Thanks

DanHolohan

They run in series.

Lambini

Wonderful article! BTW, I also have previously purchased your E.D.R. book to educate myself on all the cast iron radiators we 'inherited' when we recently bought an older property.

hot_rod

Solid_Fuel_Man said:

Because big heavy CI radiators have a lot of water and mass. So if they were all connected in series like copper baseboard the first radiator would get hot and by the time the last one did the room the first one was in would be way too hot.

Using diverter T's helps alleviate this long train and feeds each radiator (almost) equal water temperatures simultaneously.

Baseboard is low mass and low volume so the water travels much faster from the first to the last in the series loop.

The radiators or fin tube are in series in diverter T system, so each connection down the loop will see a lower temperature

One of the big advantages with diverter T is you could have a simple series loop, but still have individual control at each heat emitter.