Can't select VSD's on my pumps. Aux Energy is through the roof

[barrywalsh]

I am doing an SBEM calc for a pharmaceutical project and my Aux Energy is through the roof, I assume this is to do with the fact that I can't select VSD's on my pumps because of the centralized system I have chosen. Is there a way around this?

[Terence]

Some system types do allow for variable speed pumping.

The specification of which HVAC system can be defined with variable speed pumping is part of the NCM as listed in Table 10 of the 2010 NCM Modelling Guide, which is available for downloaded from the NCM website.

[ecoboost]

select a system type that allows variable speed pumping, don't know why they restrict you to constant speed

[JohnLloyd]

I've never fully understood why it's restricted to certain system types. The vast majority of the air based heating and cooling systems we design are variable volume systems. It's another bizarre quirk of the NCM that appears to be simply incorrect that would extremely easy to fix, but has never been.

I haven't checked but presume this hasn't changed for the 2013 regs?

[Complex Potential]

If your aux energy is through the roof then I suspect you are using a variable volume/constant volume system? Unfortunately any centralised system is going to get hammered on the aux energy due to having to size fans for room loads. The pumping makes almost no difference in comparison.