[Equest-users] PTAC and PTHP

[Eddie Corwin]

Oops, I meant to say -13*F in my previous post (in reference to the Mitsubishi 
Citi Multi-Split operating temperature)





________________________________
From: "Gary.Schrader at buildings.schneider-electric.com" 
<Gary.Schrader at buildings.schneider-electric.com>
To: equest-users at lists.onebuilding.org
Sent: Thu, November 4, 2010 3:44:38 PM
Subject: Re: [Equest-users] PTAC and PTHP

 
In addition to Eddie’s comments, I would advise referring to manufacturer’s 
documentation for heat pump performance. Performance varies by brand, model, 
capacity, and ambient conditions. I have experience with several heat pumps 
operating well into the teens. Others claim they can perform well below zero. 
Capacity charts and performance curves will tell you what the capacity is at 
various conditions. For the purposes of your model, I would ensure that you are 
using performance curves reflective of the equipment you intend to install in 
your room.
 
- Gary

_______________________________________________________________________________________________________________________

Gary  Schrader| Schneider Electric | Buildings Business | Energy Solutions | 
Engineer I
Phone: +1 913 217 8068 | Fax: +1 913 469 0206
Email: gary.schrader at buildings.schneider-electric.com | Site: 
www.schneider-electric.com/buildings | Address:  16011 College Boulevard, Suite 
212 , Lenexa ,  KS 66219 ,  USA

*** Please consider the environment before printing this email.

________________________________
 
From:equest-users-bounces at lists.onebuilding.org 
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Eddie Corwin
Sent: Thursday, November 04, 2010 2:17 PM
To: deepika khowal; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] PTAC and PTHP
 
A heat pump are a MUCH more efficiency way of heating.   The only issue with 
heat pumps are that they do not work well in cold weather (<40*F)  below this 
temperature, they are pretty much electric resistance heaters.  A lot of 
improvements have been made, for example, the Mitsubishi Citi 
Multi-Split systems can operate at temperatures as low as 13*F.  For these types 
of systems, they operate as Heat pumps at 40*F and above.  At 40*F and below, 
they use electric resistance heat to warm the air flowing over the outdoor unit 
(allowing for heat transfer between the air and the refrigerant).  So once you 
get down to 13*F they start to use a lot of electric resistance heating.  Still 
much better that pure electric resistance heating!
 
-Eddie
 

________________________________
 
From:deepika khowal <deepika.khowal at gmail.com>
To: equest-users at lists.onebuilding.org
Sent: Thu, November 4, 2010 2:52:38 PM
Subject: [Equest-users] PTAC and PTHP
HI 
I am trying to model a room with 80% glazing which has a wall unit air 
conditioner.
what will be the difference PTAC using electric heat / heat pump for heating ?
which one is advisable in terms of efficiency and energy savings?
does anyone has any thought on this?
Thanks
Regards
Deepika
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