I have a 5 year old peerless stainless steel pinnacle gas boiler. I have a side arm heater and zone valve heating with two pumps. In the winter I have to partially close the bybass valve to force the zone valve heating to work. Every four days the high temp switch pops and I have to reset it. There is one pump for the hot water circulation and one pump in the middle. I wonder if it should be on a 3 pump setup with one dedicated for the side arm heater and one for the heat? The various heating companies do not seem to know the answer, but keep charging me. Peerless has no tech support even for a customer who has Peerless 3 boilers. Some of the wall heaters get hot and others will not until I close the valve which pops the high temp limiter.
Thanks for any advice you can offer.

Without seeing how the system is plumbed I can't offer much. Could you post some pictures of the circulator and zone valve plumbing? A plumbing schematic would be the best but that's asking a lot.

Unfortunately my time at the computer is limited so I may not respond quickly. Maybe someone else would chime in.