Boiler Protection Piping

BrianF

Currently I have a Burnham Series 2 cast iron boiler with one zone of baseboard and no sort of bypass. I want to add a radiant zone and protect the boiler from the resulting low return temperatures. I've been reading on here and the internet about boiler protection, primary secondary piping, etc. There is so much and so many different opinions I'm having some trouble grasping everything.

I'm thinking about something like a Danfoss ESBE valve to raise the return temperature would the be simplest and cheapest route and wanted to know the best way to pipe it. I drew a quick sketch and wanted some help building on it. I know it isn't correct, I'm thinking a pump above the H inlet for the boiler mixing valve wired to run whenever a zone was running would work? You can see where I put one in the diagram then got rid of it. Or am I totally off?



Thank you for any assistance.





Edit: Added a 2nd drawing.

Is this a proper primary/secondary system? Would this basically solve the issue without a mixing valve since the radiant zone is small, about 10k btu?

heatpro02920

How about another option entirely, lol

just to confuse you a bit more... Heres how I would do it...



I would add a circulator to the system that is ran by an aqaustat mounted in a flat plate heat exchanger, the other side of the fphx would have its own circ that runs with the low temps zones t-stat or floor sensor.. I have better drawings at my office but heres a fast one to give you the idea...



there are obviously a few other components, like prv's, expansion tanks, ect that will be needed, this drawing is just to give you the idea of how it will work...



The 180 boiler water will heat the fphx, but only until the a-stat is satisfied, so if you set the a-stat at 110 degrees that is all it will maintain... I would use a delta t circ with the fphx so you can control the transfer better...

jonny88

rip out the boiler

only joking,a way I have used effectively would be to put a tee on the supply,if your header is 11/4 make it a 11/4x3/4 tee.coming out of the return put another tee same size .Now pipe the supply 3/4 with the return 3/4 pipe and put a gate valve in between.You should also put a thermometer on the return.Open the gate valve until you get your desired temp.If I was able I would draw a sketch but not that far advanced with computers yet.

CMadatMe

Don't Need The By-Pass

Simply use a 4-way vs a 3-way Mixing valve - simplifies piping and you get the same result.