Tekmar 360 Control- Assistance Needed

Sorry about that, I have a 260 here at my shop that I was looking at. It has the DHW function

There is no clear definition for adding that additional P-1 pump. Which I see in series with the 3 zone pumps, essentially doubling the head. I suppose adjusting the manifold valve regardless. This talks about the addition pump in the boiler loop, I think the same applies to the secondary, or mixes side of the valve.

It will be easy enough to try it both ways, with P-1 running or not. Watching the flowmeters would be an indication of what change it makes.

It's been years since I did these 4 way mix. I embraced the condensing boilers early on, never looked back. I don't recall adding that P-1. Although many were piped off a P/S series loop with close tees.

It seems that IF I thought an additional pump was required for adequate boiler flow, it would be in the boiler loop? Fig 6-12 Either way I see pumps in series.

I agree the sensor on the return, the manual shows and explains the various locations. The system supply sensor just before the first zone pump.

If you connect the loop, are the pumps in parallel. Head stays the same

flow doubles. I think the zones would want to be taken off closely spaced tees?

I would make sure zone pumps are checked.

Or this potential

At this point the system is piped, fire it up, see if it does what is expected. Hydronics is a somewhat forgiving playground. Every hydronic system has different flow dynamics based on the piping/ pumping relationship.

It's possible the control never lets the 4 way close off either side completely, so enough flow across the boiler to keep the sensor response. I know the early vane type mixers were not a 100% bubble free seal.

Will that boiler handle a no flow condition? Is it tankless coil enabled? If there is no flow the boiler is hot and isn't seeing cool return?

I'd prefer the purger at the hottest point, If it were a microbubble type it would get the job done most anywhere in the system.

I would still be inclined to run it as is, before changing things.

I know we ran many systems like this, and this drawing still shows up in some boiler manuals. I think I attached those early on in the other threads.

I don't recall if these are low, high or medium mass radiant zones. It's really only the high mass slabs that have the potential to pull the return down.

There is some rule of thumb, if the low temperature high mass zone is 10% or less of the boiler output, it probably will not pull the boiler down for excessive time.