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Discuss Circulating pump for Multi zone? in the Plumbing Forum area at

  1. Beano10

    Beano10 New Member

    Hi guys, I’m in the process of ripping out an old one pipe system and replacing it with a two pipe, feed and return. The new system will be on two zoning valves one for upstairs and one for downstairs.

    Originally i wanted the system on a single stat and single zone valve... with a flow of 0.477 l/s and a 3.9m head loss (excluding loss over the boiler) I was going to use the Grundfos Alpha 1 as I liked the idea of balancing the system from the mobile app (potentially a time saver) and the option of auto adjusting flow rate as the TRVs close.

    I’ve since changed my mind to a multi zone with upstairs and downstairs on separate zone valves and wondered if the same pump would be able to adjust flow automatically when the zone valves close.

    If I go with the two zones, at the pump the flow is still 0.477 l/s but of one zone valve closes, the upstairs loop has a flow of 0.22 l/s with 1.5m head (excluding boiler) and the downstairs loop has a flow of 0.25 l/s with a head loss of 2.1m. Would the alpha 1 be able to reduce the flow rate enough to keep the return temp to the boiler the same no matter which valves are open or closed?

  2. king of pipes

    king of pipes Trusted Plumber GSR

    Providing its is piped correctly then yes . Kop
  3. Gasmk1

    Gasmk1 GSR

    why not go wiyh low loss header vaillant boiler and the vailalant controls rally easy to multizone
  4. gmartine

    gmartine GSR

    A typical situation where hydraulic seperation is required, close couple tees would probably do it though don't you think Gm1?
  5. Beano10

    Beano10 New Member

    Thanks for the replies...

    In terms of piping it's a vented S-plan system with a 24kW Worcester Greenstar Ri boiler. There's a bypass (gate valve) fitted which I hoped would maintain flow when the zone valves close.

    I was hoping to add an additional zone valve in parallel with the existing CH valve? Would I need a low loss header/close couple tees for this to work?
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