Help re Warning 'unusual level of insulation' HW cylinder storage loss entry Apache systems - kWh/l.day vs kWh/24hrs

[mhanson]

Can someone please look at this for me? Am rather concerned to make sure i am entering the correct unit for HW cylinder storage loss entry in Apache systems and think the guidance could be clarified. Alternatively perhaps it is the Warning message in the command line that needs correcting...?
Full issue is as follows:
Essentially in ApacheSystems> Hotwater i've entered a value for HW cylinder storage loss of (in this case) 0.0075 kWh/(l.day) but on running Compliance (SBEM) the scroll text in the command line popup window says
"WARNING: Check the input monthly storage losses for HW system: SYST0001-DHW as they would correspond to an unusual level of insulation"

The above figure was derived from an example of 1.57kWh/day standing loss for a 210 litre cylinder (Megaflo Eco, 60mm factory insulant). So 1.57 / 210 should give losses in units of kWh/litre.day Seemed a reasonable approach to me.. but then I get the error reported above...
So checking lots of guidance, such as for VE compliance (for example http://www.iesve.com/downloads/help/The ... liance.pdf section 7.2.6) suggests that this is actually an entry for 'DHW storage tank loss factor' and that this should be calculated from the combination of 'storage loss factor' x 'volume factor Vf' . If I was to take the closest entries for 60mm insulant(0.0152) and 210volume (0.817) then 0.0152x0.817 gives 0.012 factor which is totally different. Been getting confused re this due to lots of different units / terminology being thrown around in various guidance docs and support texts.
Can someone please clarify this for me?
By the way, strangely the orginal figure above (0.0075) also gets rounded to 0.002 in the BRUKL report. ( Why...? )

[Wasted Energy]

Can't see what you are doing wrong there.
I follow the same approach.
Not that I can ever beat the notional building - which is another issue.

[mhanson]

Cheers @WastedEnergy. So you agree with my use of 0.0075 kWh/(l.day) value for DHW storage tank loss being derived from calculating kWh/day standing loss / volume...? (1.57/210 when 1.57kWh/day cylinder standing loss and 210 litre cylinder)
Frankly would have appreciated more clarity and support from the Guidance docs, and less weird warnings from the VE-compliance really. I'm also wary that it would be just the thing that gets thrown up in an audit...

Can't see what you are doing wrong there.
I follow the same approach.
Not that I can ever beat the notional building - which is another issue.

[PCully]

Hi,

First to note this warning is being output by SBEM rather than VE so it's not something I can debug for you or explain. They will have their criteria for flagging up a warning when you choose to enter the tank volume and storage losses directly in this way but I don't know what the rule is.

The input in VE is kWh/l.day and should be calculated base don the losses for your defined storage volume. This is then converted by VE to MJ/month which is read by SBEM in the input file, calculations run and then I believe they process the results back the way to give a kWh/l.day which strangely comes out different to what you entered going by your account.

Details of the calculations SBEM follows can be found in the SBEM Technical Manual which is very useful should you need to query any of the simple calculations that are run in SBEM.

http://www.uk-ncm.org.uk/filelibrary/SB ... 0Nov15.pdf

Phil