Modelling CHP for Domestic Water Only

[mlmJonathan]

Terrence,

when you say click the option same as "space heating" is thaat telling IES that the Heating method is the same for both heating and DHW.

the issue i am having is i want to use Boilers for heating and CHP for domestic water.

also in your results you are showing the electricity generated but not the energy consumption of the CHP unit would you be able so show me a ss of that ?

Also are the inputs in the apache part of the renewables linked to the SBEM part or completely seperate ?

[Complex Potential]

I know I'm not Terence but I'll give this a go. For what it's worth I'm hedging my bets on this being a glitch in IES 2014 which has been fixed in 2015.

Terrence,

when you say click the option same as "space heating" is thaat telling IES that the Heating method is the same for both heating and DHW.

No, it is just saying that for the DHW system, the heat source defined within the heating tab is what gets used for the DHW.

the issue i am having is i want to use Boilers for heating and CHP for domestic water.

also in your results you are showing the electricity generated but not the energy consumption of the CHP unit would you be able so show me a ss of that ?

The fact that the CHP is showing generated electric means it is correctly linking to the DHW in Terence's model. The actual figures are meaningless given that he left most of the inputs on default settings.


Also are the inputs in the apache part of the renewables linked to the SBEM part or completely seperate ?

They are completely separate.

[mlmJonathan]

Hi Guys,

I just tested this in VE 2015 and it was working the same in Apache and VE Compliance. Here are my inputs

DHW System



CHP



Room conditions in Apache (set up to be the same as the activity in VE Compliance)



System tab in room data



And here are the results for CHP

93 litres per hour per person of DHW ?? does that seem correct

[mlmJonathan]

I know I'm not Terence but I'll give this a go. For what it's worth I'm hedging my bets on this being a glitch in IES 2014 which has been fixed in 2015.

Terrence,

when you say click the option same as "space heating" is thaat telling IES that the Heating method is the same for both heating and DHW.

No, it is just saying that for the DHW system, the heat source defined within the heating tab is what gets used for the DHW.

if thats the case how does it define how much goes towards the Domestic hot water and how much goes towards the heating ??

the issue i am having is i want to use Boilers for heating and CHP for domestic water.

also in your results you are showing the electricity generated but not the energy consumption of the CHP unit would you be able so show me a ss of that ?

The fact that the CHP is showing generated electric means it is correctly linking to the DHW in Terence's model. The actual figures are meaningless given that he left most of the inputs on default settings.


Point taken

Also are the inputs in the apache part of the renewables linked to the SBEM part or completely seperate ?

They are completely separate.

Reason i asked again regarding this was the comment that SBEM and apache were giving the same results however you input different information so i was wondering how this was achieved

[mlmJonathan]

I guess right now i am looking for confirmation that unless you have VE2015 (i am also on 2014) you cannot replicate a CHP running DHW ??

[Complex Potential]

That's what we're waiting on Terence coming back to tell us. He's going to try using 2014 and see if he gets the same problems we are.

As for the 93l/h/person, it's just a random figure plucked out of a template for something, possibly a changing room, it's not important.

if thats the case how does it define how much goes towards the Domestic hot water and how much goes towards the heating ??

Because that system is only applied to the DHW within the system tab of your room templates.

Reason i asked again regarding this was the comment that SBEM and apache were giving the same results however you input different information so i was wondering how this was achieved

I don't remember that comment, SBEM and Apache CHP modelling is very different.

[mlmJonathan]

yeah at the top of his post it says he tested it on Apache and VE complience and they work the same.

I understand the other points you are making.

[Complex Potential]

Ah right yes I see. Terence simply meant that the functionality was working the same for both Apache and VE Compliance which is as it should be (DSM not SBEM by the way). He didn't mean that it was giving the same result.

[mlmJonathan]

oh i see. makes sense then. My head is so wrapped up in this CHP i am not thinking properly ha ha

[Terence]

Testing it in VE 2014 the results are the same as my test in VE 2015 (i.e CHP links to DHW in Compliance and also Apache)

If you want to have a look at the settings in my test you can download a CAB archive of the project here: http://upload.iesve.com/uploads/8617/20 ... 6Jun15.cab

To answer your question Jon, you can ensure that only the DHW is linking to the CHP by creating a new apache system and then assigning that as your system for DHW as shown in the following screenshots.

Note the Apache System is just used for DHW. Not Space Heating



This is only assigned through thermal templates as a DHW System



With this setup the "Main System", is providing Heating/Cooling to the space and it is not linked to the CHP as the CHP box is not ticked for this Apache System.