RemRate Water Furnace modeling problem

Replies to This Discussion

Permalink Reply by Michael J. Mayhew on August 4, 2011 at 7:57am

One would be tempted to put in 500%, but refrain, the stated COP is just for the unit, not the HP system, which will include pumping power and other distribution losses.  Probably system COP closer to 3.

• ▶ Reply

Permalink Reply by Brian Christensen on August 5, 2011 at 1:42pm

Hi Elizabeth -- If you look at the last page of this article (http://www.luntmarymor.com/condensing_heaters.pdf), you'll see a nice description of how EF is measured.  From this, and factoring in the additional consumption that Michael mentioned, you can probably come up with a reasonable approximation of the EF for your scenario.  The toughest part may be to figure out the standby losses, if the DHW is a tank-type system.

Note that in REM the EF is entered as a decimal, not a percentage -- and for a heat pump, the decimal will be larger than 1.0.

• ▶ Reply

Permalink Reply by Dave Dysson on August 5, 2011 at 6:49pm

I was looking at REM/Rate and the GSHP only needs COP entered. It looks like you only need to model the type of water heater you are using for EF and also check desuperheater in the heat pump section if they are coupled.

• ▶ Reply

Permalink Reply by Dave Dysson on August 5, 2011 at 7:15pm

Also to add the pump watts. Are you using the GSHP to supply 100% of the domestic hot water?

• ▶ Reply

Permalink Reply by Elizabeth Guinn on August 8, 2011 at 5:02am

Thanks for the help.  Didn't want to reinvent the wheel if someone had already been down this path.

• ▶ Reply