DHW Tandem System Generation Bivalent

[VirtualEngineer]

Hi all

I'm looking into achieve a 20% renewables target for a hotel and I'm having some difficulty as the DHW demand/energy usage is quite high.
Initially I would've liked to apply an ASHP on 100% of the DHW, but unfortunately there aren't many on the market that are really designed for DHW 100% production and given that most ASHP's designed for space heating have quite poor efficiencies supplying 100% DHW, I think we might have to split production.

Essentially we'll have the ASHP heat water 10-38 °C and then stand alone gas fired to heat from 38-65°C, I can't seem to find a way to apply this in VE SBEM, is there something I'm missing or is there another method which should be used?

Thanks for your help

[PCully]

Hi,

When running SBEM Compliance you don't have that level of detail on the definition of a hot water system. A few options that I think would be sufficient

- Make the hot water system bivalent and define the two heat sources (and fuels) with your estimation of the breakdown in % load being met
- stick with a single heat source on the dhw system and adjust the efficiency to represent the overall system you have designed.

I'd always suggest you run a query such as this past you accreditation scheme to get their take on your approach within the building regulations

Phil

[VirtualEngineer]

Hi Phil

Thanks for your reply, I've used the first solution you mentioned and everything looks to be working as it should. I've now specified DHW System in tabBTM as a bivalent system sharing the % load between systems with a different fuel for each.

Thanks for your help

[Philco49]

Hi Phil

I've been trying to find a solution to this for a while.
When I try setting the bivalent option i get the message "Please note that VE-SBEM does not yet support bivalent Hot water systems"

Can you say what effect this may or may not have on the output results?

Thanks
Phil