Any advice on how to factor a gas fireplace into a Wrightsoft Manual J model? 

Seems like it would reduce the required heat from the central gas forced air system in that room. But not quite sure how to include this in the model. 

Any advice is appreciated. This is my second Manual J model.

Bachi

Ultimate Home Performance

Views: 381

Reply to This

Replies to This Discussion

I would not include it.  Given that it is likely much less efficient than the gas furnace, you don't want to count on the occupants using it when the outside temperature approaches the design temperature.  However, if it is atmospherically vented, you will need to include the flue in the air leakage model.

Dave

Most fireplaces a just a hole that lets heated/cooled air out chimney.  If the heated hole(fireplace) is use much just add more CFM to vent rate.   Most fireplaces are for looks and not a  real way to heat the building (eye candy).   I find a open fireplace is negative 5%  Eff.     

I agree, that fireplaces are for looks and not heat.  There are those who insist on having a fireplace, especially gas, where the vent is always open.  The fireplace needs to be covered with insulation to stop heat/cooling loss.  Fireplace Fashion makes an insulated, magnetic fireplace cover to be used when the fireplace is not in use.  This stops ;the air flow in and out of the chimney, thus stopping any heat or cooling lost dollars.   More information can be found at fireplacefashion.com.

Wrightsoft has an option to include a fireplace in a zone.  I would use that option since it complies with the Manual J instructions.  If you use some other method (hole or heating source) you should make sure your method complies with Manual J.

What kind of gas fire place?  Gas logs... in "generic brick fireplace" with dampers that are left open?  Or a sealed combustion fireplace insert?  With a pilot or pilotless?

If you've got a high performance envelop - and an efficient sealed gas insert.... they can do quite well in heating one end of the house.... and not be a massive air leak.  We have two...in our house.. and it tests at 2.8ACH50.

If the units are cheap - and don't seal up... treat them as a brick fireplace with damper stuck open.

I put a 2 Inch foam cover and painted it black and dropped the heat loss by 3/4.  You can not use it a fire place till remove the cover.  Most cast iron damper are so bent I can not close.   Just say NO to fireplaces and put in the 90%  heating system.   Over 1/2 the high CO probems I go to are with fireplaces 

Sealed combustion fireplace insert. No pilot. I believe it can be hooked up to a room thermostat. 

some can get up to 92% with PVC vent.   Some use 24 volt thermostat that can be +- 2 dead band with heating thermostat

When you model,  add a small additional area  -- say less than 10 sq inch of for possible air leaks...(that should be real high)... be safe and model the fireplace at 60%... efficient.  It really should be used just occasionally not as the primary heat source... 

With an insert - it really isn't the driver for your heat loss in the house.

ACCA Manual J does not consider any heating (BTU gain to a room) from a fireplace.  Manual J only allocates infiltration to the home caused by the fireplace's construction quality.

I think that was part of his concern.  Its a sealed combustion unit.  So the infiltration that might be used for an ordinary fireplace is going to be off the chart.  If its a new home with high end sealed combustion fireplace, correctly installed per manufacturers design... the infiltration might be closer to that of a tankless hot water heater.

A.  The point is that ACCA Manual J does not model for the Btu gain from fireplaces.

B.  Fireplaces are a part of the infiltration load in ACCA Manual J.  You have a choice as to construction quality - Tight, Semi-Tight, Average, Semi-Loose and Loose.  It is all spelled out in the actual Manual J manual published by ACCA.

RSS

Latest Activity

Jim Gunshinan posted a blog post

Allison Bailes—Common Problems with Cold Weather Ventilation

When I woke up Saturday morning, the temperature outdoors was -40 degrees…See More
9 hours ago
John Proctor replied to Tray Biasiolli's discussion Two-stage furnace, control at furnace or thermostat?
"Ted -- The startup losses on modern furnaces are much smaller than the old days. I would suggest a…"
11 hours ago
Profile IconVeronica Pembleton, Thom Phillips and jeff greenberg joined Home Energy Pros Forum
12 hours ago
Barbara Smith's video was featured

RESEARCH RESULTS: Improving installation/maintenance practices

We conducted research on residential heating and cooling systems in Minnesota homes to help improve installation and maintenance practices for furnaces, air ... Seventhwave
12 hours ago
Jim Gunshinan's blog post was featured

Using God Talk—or Not—to Help the Planet?

I am always impressed with the work of Susan Shelton and the Shelton Group. So an email message…See More
12 hours ago
Jenna Bader's event was featured
Thumbnail

Zero Net Energy Virtual Conference, Jan. 25 & 26, 2018 at Online Webinar via Zoom, Facebook Live, and YouTube Live

January 25, 2018 to January 26, 2018
Devoted to the All-Electric, Solar-Powered Building TypeA FREE On-Line Conference using Zoom: …See More
14 hours ago
jeff greenberg replied to mark avila's discussion Aeroseal Homeseal Pro unit for sale?
"Mark: My client has one for sale. very lightly used but huge discount.   Where are you…"
yesterday
Jenna Bader posted events
Friday
Sean Lintow Sr replied to mark avila's discussion Aeroseal Homeseal Pro unit for sale?
"As I recall you have to be a Aeroseal listed "distributor" aka installer to get the…"
Friday
Paul Raymer posted an event

Radon Protections in New Homes at On line

January 30, 2018 from 1pm to 2pm
Radon-resistant construction is becoming a focal point in the high performance building industry.…See More
Thursday
mark avila posted a discussion

Aeroseal Homeseal Pro unit for sale?

Hello,We may be in the market to purchase a used machine should someone have one for sale.Cordially,See More
Thursday
Robert Zockoff liked Tray Biasiolli's discussion Two-stage furnace, control at furnace or thermostat?
Thursday
Profile IconKevin Jacks, Christine Elovecky and Bryan McIntyre joined Home Energy Pros Forum
Thursday
Kevin Jacks liked Diane Chojnowski's group Job Board
Thursday
Scott Doyle liked David Butler's discussion RESNET gets serious about modeling platform consistency
Thursday
Quinn Korzeniecki posted an event

BPI Retreat at HPC New York 2018 at Saratoga Springs, NY

February 12, 2018 from 12pm to 4pm
BPI will be hosting a retreat for BPI GoldStar Contractors, Test Centers, Proctors, and Certified…See More
Thursday
Quinn Korzeniecki added a discussion to the group Building Performance Institute (BPI)
Thumbnail

BPI to Host Retreat for Stakeholders on February 12th

BPI will be hosting a retreat for BPI GoldStar Contractors, Test Centers, Proctors, and Certified…See More
Thursday
Rhett Major posted an event
Thumbnail

Building Analyst - Energy Auditor Class at Conservation Consultants, Inc.

February 26, 2018 at 8am to March 2, 2018 at 5pm
Building Analyst - Energy Auditor class for BPI Certification, using Saturn Resources On-line…See More
Thursday
Barbara Smith's video was featured

ACEEE Report: How to Talk About Home Energy Upgrades

How can home energy assessments lead to more energy efficiency upgrades? Using a behavioral science approach to answer this question, we conducted an online ...
Thursday
Profile IconMichael W. Ford and Rob Vehring joined Home Energy Pros Forum
Wednesday

Photos

  • Add Photos
  • View All

© 2018   Created by Home Performance Coalition (HPC)   Powered by

Badges  |  Report an Issue  |  Terms of Service