Pagin Mr. Brad White

Josh_10

Hey Brad will this work?

Brad White_9

Hey Josh

Q.: What is the 5 gallon tank for? (The Rinnai is an instantaneous type I assume so maybe that answers it.)

I do not think 5 gallons is enough buffer, just a gut check. I usually use about 3-5 minutes of flow rate. You seem to have 7.5 GPM so a 30-40 gallon tank might give your Rinnai a rest.

What is firing the Rinnai? Might you need to have the pump going IN to it to keep the flow switch happy? Does the primary run to fire the Rinnai based on tank temperature?

Expansion tank and relief valve are assumed of course. Details but important. Also presuming sensors downstream of your secondary circulator running your injection circulator.

On the whole I do not see why that would not work. You could fit all of the injection hydronics except the tank on a 4x4 sheet of plywood.

Just some thoughts.

Josh_10

Well actually brad my thought is that I just need a slight buffer between the variable speed injection pump and the Rinnai. If I just pipe the variable speed injection pump right out of the Rinnai the flow can drop too low for the Rinnai to fire.

Brad White_9

That makes sense, you need the primary flow.

Good call. I might still fire the Rinnai by a tank aquastat (bigger tank is just my way, the small one may work as a low-loss header). The aquastat would run the primary at a rate sufficient to trigger the Rinnai.

I think as a package that will satisfy the control aspects nicely. Standby losses are inherently low in the instantaneous type heaters so cycling is less of a concern, it is what it is.

Paul Rohrs_5

A couple of things

I tried this a few years ago and Rinnai's engineering seemed unwilling to endorse. You might want to double check that they will warranty components.

I would highly recommend that the secondary loop be constant flow. Flow-setter on the outlet of the Rinnai to set maximum injection flow rate. Constant flow on the P2 circ and the P1 variable speed will provide the outdoor reset water temp.



Regards,

PR

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"