Delta T pumps: Boiler circuit and outdoor reset.

TAG

Am I correct that a Mod Con boiler (Viessmann 200 in my case) wants a static boiler circuit pump going into the LLH? Grundfos 15/58 3 speed is on the Viessmann recommend list .. I'm not sure why you would want ... or need different speeds ..unless this recommended pump is on the list for various models of boilers? Same with the indirect DHW tank circuit -- You would want a single speed for what is a static load/head. Am I missing something?

Also -- with ODR it seems that the Delta T pumps could further "tweak" a particular zone .. or am I wrong and it throws off the ODR of the boiler.

It seems to me that if I set up my new system with a constant speed pump feeding the manifolds to the main part of the house (Warmboard) using ODR of the boiler. I could then use two of these new Taco Delta T pumps to feed the dedicated manifolds for my slab and retrofitted plate setups .... it would just take the water temp from the boiler and maintain the set delta for each. The pumps being controlled with floor sensor for the slab and room thermostat for the plate retrofit.

I would think the delta T pumps used off of a boiler with ODR -- would screw it up (the boilers logic).

My Warmboard manifolds will have some zone valves and I can see how this could be helped with a Delta P pump --- if there was a possibility of major flow differences.

It seems that with proper layout these new T pumps sort of do an outdoor reset based on load.