[Equest-users] Modulating furnace

[Nick Caton]

I would also suggest to investigate/review/modify the system's library FURNACE-HIR-FPLR curve to fit actual performance.  I'd have to plot it to visualize, but from there you could establish a curve fit that effectively forces your minimum turndown by raising HIR as you approach zero load  - crunch the math in a spreadsheet, and remember this curve is normalized to the input HIR efficiency (at full load).
~Nick

[cid:489575314 at 22072009-0ABB]

NICK CATON, P.E.
SENIOR ENGINEER

Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
www.smithboucher.com

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Hall, Brendan
Sent: Wednesday, March 12, 2014 3:10 PM
To: Michael Campbell; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Modulating furnace

Right, that is a bit trickier. I would say that it is going to be very infrequent that it would call for a load between 0 and 6%. The AHU fan can only go down so much so by the time it comes out of economizer you should have more than enough load to justify it running. I guess the question would be if you had something with a much lower turndown. The curve that modifies the HIR(PLR) is pretty much linear even though it is in cubic form so there is no variation in efficiency as you go down in capacity, but check that against your equipment info. Not a whole lot of options, but I'm sure that's why you asked in the first place.

Brendan Hall,  PE, LEED AP BD+C
Engineer, Mechanical
karpinski
ENGINEERING
3135 Euclid Avenue
Cleveland, OH  44115
P  216.391.3700<tel:216.391.3700> Ext 3111
E  bhall at karpinskieng.com<mailto:bhall at karpinskieng.com>
W www.karpinskieng.com<http://www.karpinskieng.com/>

From: Michael Campbell [mailto:mike at sustainablesolutionscorporation.com]
Sent: Wednesday, March 12, 2014 3:49 PM
To: Hall, Brendan; equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Cc: mike at sustainablesolutionscorporation.com<mailto:mike at sustainablesolutionscorporation.com>
Subject: RE: [Equest-users] Modulating furnace

Thanks for the reply.  However, to clarify, this is an AHU with gas furnace heat, so there is no boiler.

Mike Campbell, E.I.T., LEED AP O+M
Sustainability Specialist
Sustainable Solutions Corporation
Office: 610-569-1047<http://610-569-1047/>
Mobile: 609-923-1743<http://610-569-1047/>
www.SustainableSolutionsCorporation.com<http://www.sustainablesolutionscorporation.com/>
Sustainable Solutions Corporation is WBENC and BCorp Certified.

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From: Hall, Brendan [mailto:BHall at karpinskieng.com<mailto:BHall at karpinskieng.com>]
Sent: Wednesday, March 12, 2014 3:45 PM
To: Michael Campbell; equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: RE: [Equest-users] Modulating furnace

Under the boiler, set the min ratio = .06.

Brendan Hall,  PE, LEED AP BD+C
Engineer, Mechanical
karpinski
ENGINEERING
3135 Euclid Avenue
Cleveland, OH  44115
P  216.391.3700<tel:216.391.3700> Ext 3111
E  bhall at karpinskieng.com<mailto:bhall at karpinskieng.com>
W www.karpinskieng.com<http://www.karpinskieng.com/>

From: equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org> [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Michael Campbell
Sent: Wednesday, March 12, 2014 3:41 PM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: [Equest-users] Modulating furnace

What is the appropriate way to model a gas furnace that modulates with a 16:1 turndown?

Thank you,

Mike Campbell, E.I.T., LEED AP O+M
Sustainability Specialist
Sustainable Solutions Corporation
Office: 610-569-1047<http://610-569-1047/>
Mobile: 609-923-1743<http://610-569-1047/>
www.SustainableSolutionsCorporation.com<http://www.sustainablesolutionscorporation.com/>
Sustainable Solutions Corporation is WBENC and BCorp Certified.

This email message and any attachments are for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message and any attachments.

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