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Mitsubishi M series vs P series

cweedon | Posted in Mechanicals on

I am coordinating construction of a new municipal garage in zone V.
The heating load is 36,000 btuh.  The intent is to only heat the space to 50 degrees.
I understand the P series is more robust than the M series, but what does that mean in the real world? 
Using two FH18’s to meet the load would seem to provide a significant improvement in the HSPF (7 to 9 in zone V).  With that difference we could plan less solar PV to get to net zero. Thoughts? Thanks

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  1. willymo | | #1

    Don't know the answer, but replying partly to bump, but also to ask: is the 36K heat loss at 50° or at 65-70° (eg "normal" temps)?

    1. willymo | | #2

      Also, the minimum heating temp on these is 50°. Whatever you decide, you should check the minimum output, so that they don't cycle excessively in the fall/spring.

  2. cweedon | | #3

    The 36K heat loss was calculated at 68 deg. The building is now built and we did use M series.
    Seems to be working fine.

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