New Boiler and slight change to system installed in 2005

wattz · June 7

I have two questions about an in-floor Radiant system that was installed before I bought the place Cir 2005 or so. The home is about 4200Sq feet and was running a Buderus GB-142/45. The Boiler has been giving us problems off and on for the last 11 years. It has finally quit and I took the opportunity to try to update the system a bit.

as you can see the system was setup for a high temp primary loop with a injection pump to push into the secondary loop. as well as a system pump and a second system pump off the Tee to the boiler. I am trying to simplify the system and installed a hydraulic separator and just one system pump.

I already know (now) that I messed up the hydraulic separator since I reused the piping the hot side is currently coming into the bottom left in the primary loop and out the top left and the same for the secondary feed side for the hot is the bottom right and return top right. I did a test run and the heat is making its way over but not as well as before with the old system. Is that mostly because I need to swap both of the in and out from the primary and secondary loops? or did I also make a mistake by taking out the pump on the primary loop. The replacement boiler is a Rinnai I-Series 150,000 BTU Combi.

Any insight would be fantastic.

Alan (California Radiant) Forbes · June 7

I don’t know if it would solve your problem, but it’s important to set up counterflow in the Caleffi separator. Switch the pipes on the left side.

And if you removed a pump on the supply side, what is left to move the water? You need something more than gravity.

I see that you used a DWV (drainage) 90 on your piping. Not the end of the world.

hot_rod · June 7

does the boiler have a pump inside, or did it come with one?

Pipes like this hot into top, return from bottom. On both boiler and system side

So a boiler pump and system pump

Is it a two temperature system still?

Kaos · June 7

Looks like you kept the closed spaced Ts from the original boiler. You either have closed space Ts or hydraulic separator, not both. With the way you have, you won't get much if any flow through the sep as all would just go between the two closed spaced Ts.

I would remove the closed spaced T and replumb the primary loop and also fix the ports on the seperator. That will fix all your issues.

The combi has an internal circ. There is no need for any extra circs beside the Alpha for the secondary loops.

wattz · June 8

Thank you everyone for the insight, I think Kaos has hit it on the head there is a circular inside the cabinet of the Rinnai and it does seem like the water instead of going around the primary loop its trying to just loop around the Closed spaced T from the old Buderus boiler. I will just cut out the T and stick two 90's on the feed and return from the boiler and flip both the primary and secondary inputs into the separator.

As far as running two temperatures no I don't believe it ever needed two. its mostly just this primary loop and main heating secondary, there is a third loop that connects to the primary that runs all the way to my pool for heating, but since I am in PA I would never be heating the pool and the house at the same time.

hot_rod · June 8

Rinnai has pretty good piping schematic in the manual or online, also. It should show they header or a seperator piping options.

GGross · June 8

looks like you are piped with close spaced tees, and then to a low loss header? I would change that personally, but if you need it that way for some reason you will need an additional pump on that side of the llh.

New Boiler and slight change to system installed in 2005

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