HVAC Search

Christopher Rath

Spring, 2002

This page is getting a bit stale, and as a result I am receiving phone calls and emails from people looking for more current information. See the bottom of this page for a quick update that attempts to answer the most common questions is am receiving.


This page attempts to capture what I've learned while attempting to replace an oil fired furnace, oil fired hot water tank, and central air conditioner.  All in all this has been a highly frustrating experience—something akin to dealing with a car salesman—and surely my gleanings can help others avoid the pitfalls into which I have fallen.  There are a couple of MS Excel-based tools contained below: both of which should be provided by the companies selling these appliances, but which are not.  Good luck in your own search.

The Catalyst

Several years ago we purchased a 30+ year old house.  It had an existing mid-efficiency oil furnace, oil hot water tank, and central air conditioner.  The furnace was in the range of 15 years old, but we found no way to precisely determine its age.  This past winter the oil pump gave us trouble, and this resulted in a small oil spill.  Fortunately, the concrete floor around the furnace is well painted, and so none of the oil penetrated the concrete and we were able to contain and completely clean up the spill.  The possibility of an oil leak has been my only reservation with the existing oil-based HVAC system, and a desire to eliminate any possibility of another such accident started me on a search to replace the system with natural gas appliances.

A historical note: when we purchased the home, we had a natural gas line installed in the house so that we could use our gas stove and gas dryer, and it has always been our long-term goal to move to gas appliances.


While my wife and I do not consider ourselves tree-huggers, we do try to practice responsible use of our resources and the installation of high efficiency appliances is one of the ways we can do this.  The following comments apply to how manufacturers report efficiency in Canada. See the Canadian EnerGuide Website for more information.  For all practical purposes, the Canadian EnerGuide ratings are the same as those used in the United State.

The overall efficiency of furnaces and hot water heaters is measured using something called the “Annual Fuel Utilization Efficiency” (AFUE) factor.  This differs from the raw efficiency of the appliance and is especially important when evaluating a hot water heater: the water in a hot water tank cools off when hot water is not being consumed, and the water is then periodically reheated; this loss is factored into the AFUE (which provides an estimate of the unit’s net efficiency).  The higher the AFUE factor, the better.  The factor is expressed as either a decimal number less than 1 (but greater than 0) or a percentage.

Air conditioners have their efficiency measured using “Seasonal Energy Efficiency Ratio” (SEER) units.  The higher the SEER rating, the better.

Quotes From Installers

The way the HVAC market works here (Ottawa, ON, Canada) is that contractors/installers come and visit your home and provide you with a quotation on what the appliances and installation costs will be.  They do not generally split the installation cost from the cost of the appliances; rather, they only quote you the installed cost of the appliance.  This can make it difficult to compare quotes from different contractors; however, that isn't the worst of it.

The gentleman (I haven't encountered any woman working in the trade, but there must be some) who visit your house to provide the quotation are salesman.  They are not competent to authoritatively tell you what the building code says about the installation of your HVAC system (i.e., they are not licensed HVAC technicians).  They will give their opinion, and in the way of salesman will make promises to you about the installation of the system—which will later turn out to be lies.  I speak from personal experience in this matter: having been duped once before when purchasing a high efficiency furnace for a previous home.

To ensure that you are able to properly evaluate the claims the salesman makes regarding the installation of your HVAC system, I strongly recommend that you obtain a copy of the local building code and read what it has to say.  This doesn't make you an authority on the subject, but it does mean you will be more knowledgeable than the salesman.  In Ontario, Canada, the building code is available online (I will post links to other relevant building codes if readers will send them to me):

  • The Ontario Building Code (Building Code Act, 1992)
  • Note that most Canadian building codes, including the Ontario Building Code, defer to the Canadian Standards Association's “Natural Gas Installation Code” (CAN/CGA-B149.1); which is unfortunately not available online.  Printed copies can be ordered from the CSA Website or your local bookseller.

    Tips For Dealing With Contractors

    Here are a few thoughts regarding getting the most out of your dealings with HVAC contractors:

    Warrantee vs. Price

    Some contractors offer 5 or even 10 year parts and labour warrantees on some of the HVAC systems they sell; however, in the quotes I received during this search I found these contractors to be quoting higher prices than those companies who only offer the manufacturer’s warrantee terms.  My own decision was to purchase at a lower price today, but plan on purchasing a service package from the contractor for the years following the expiration of the manufacturer’s warrantee.

    The practice of utilizing a service package defers laying out my cash over the lifetime of the unit; instead of paying it all up front.  Not everyone agrees with this approach, but it I'm happy with it; and that’s all that matters, since it’s my money. <smile>

    Hot Water Heaters

    Hot Water Tanks

    The classic North American hot water tank is a mid-efficiency device when its AFUE rating is examined.  Tank-based hot water heaters typically have AFUE ratings in the 0.53–0.63 range. The absolute efficiency of a tank water heater is much higher, but heat loss as the tank sits overnight contributes a significant energy/efficiency loss.  Given that we have four children, we believe we would require a 189 litre (50 US Gal.) tank. Tanks in this size have AFUE ratings in the 0.53 to 0.60 range. 

    There are two main types of gas-fired hot water tanks: power-vented and non-power-vented.  I am told that power vented tanks are quite noisy.  I believe this anecdotal comment is borne out by the fact that Rheem sells a sound reduction kit for their power vented water tanks. The advantage of a power vented tank is that it can be vented through PVC pipe out the side of your home. If you decide to purchase a power vented water heater be sure to determine in advance how noisy it will be.

    This article does not consider these units in any further detail, as information about them is widely available.

    Tankless Hot Water Heaters

    Business travel has often taken me to Western Europe.  This has exposed me to tankless water heaters (so-called instantaneous water heaters); used there because of their small size and reasonable efficiency. In considering a replacement for our oil fired water heater, we initially considered tankless water heaters simply because of this previous exposure (without any prior knowledge of potential higher efficiencies).

    A quick search of the Internet turned up several natural gas fired tankless water heaters, and I determined that if a suitable unit could be found it should result in approximately 25% less natural gas being consumed (due to AFUE ratings being 25% better).  At the time of writing (spring, 2002), there are two primary natural gas tankless product lines to choose from in North America: Bosch and Takagi—one will also encounter the AquaStar brand, but these are simply re-branded Bosch and Takagi units.

    Choosing A Unit

    Tankless hot water heaters work by heating the water a specified number of degrees, as measured against a water flow rate.  The faster the water flows through a tankless heater, the less heat the unit is able to pass along to the water.  These specification sheets for these units typically show a small table with 5 or 6 different flow rates and the corresponding number of degrees the unit is able to heat that water. 

    Here are the ratings for some models sold under the AquaStar brand name.  Notice how the AFUE is lower than the efficiency of the unit; the 125B has an especially low AFUE due to the fact that it has a pilot light (and the gas wasted running the pilot light results in a lower net efficiency).

    Specifications by Model (from the Controlled Energy website)
    Model Efficiency AFUE Gallons per Minute (Degree Rise):
    45° 55° 65° 75° 90°
    240FX 82% .81 5.3 4.4 3.8 3.3 2.9
    125B 82% .69 4.0 3.3 2.8 2.4 2.0
    125FX 80% .78 4.0 3.3 2.8 2.4 2.0

    What follows is the method I used to determine which models were suitable for our family.

    The situation in which the flow of hot water is most important to us is when we are taking a shower.  One of the pleasures of middle-age is taking a hot shower, and we have a standard 2.5 gallon per minute (gpm) shower-head.  This means that when the shower is running the water heater must deliver enough hot water, at a hot enough temperature, in order to mix with cold water and provide a satisfactory shower.

    The following formula holds true when two streams of water which differ in temperature are mixed:

    (Flow_Rate_1 * Temperature_1) + (Flow_Rate_2 * Temperature_2) = (Flow_Rate_1 + Flow_Rate_2) * Final_Temperature

    This can be transformed as follows, to allow us to calculate the temperature that results from two streams of water mixing:

    Final_Temperature =

    (Flow_Rate_1 * Temperature_1) + (Flow_Rate_2 * Temperature_2)

    (Flow_Rate_1 + Flow_Rate_2)

    To determine the water flow of our shower head:

    1. I walked through the house to ensure that no water was running from any faucet or through any appliance (e.g., dishwasher, clothes washer, etc.).
    2. I noted the water meter’s reading.
    3. I run the shower at its maximum flow rate for 5 minutes: I turned the cold water all the way on, and then increased the hot water until I observed that the maximum flow rate had been achieved.
    4. I turned off the shower and again noted the water meter’s reading.
    5. I divided the number of cubic meters of water consumed by 5 (since the water was run for 5 minutes) to determine cubic meters per minute.
    6. I then converted the cubic meter measurement to US gallons per minute (which is how the tankless water heaters are rated).
    7. This produced the flow rate input for my water temperature workbook, below.

    To determine the final water temperature we needed to satisfy our hot water requirement:

    1. I ran the shower and adjusted it so that the temperature was slightly warmer than we would typically shower with. 
    2. I then held a thermometer in the shower stream and measured the temperature (113° F.).

    To determine the cold water temperature (you should perform this step during the winter in order to determine the worst case cold water temperature):

    1. I ran the cold water for 5 minutes.
    2. I then held a thermometer under the water flow and measured the temperature (39.2° F.).

    I put the above formula and my water measurements into a small MS Excel workbook, and plugged in the values for each of the hot water heaters to see if they could deliver sufficient hot water.

    Click on the image to download the water temperature calculator workbook (Excel 2000 format) [12KB].

    As you can see in the above worksheet snippet, the T-K1 will deliver sufficient hot water to produce a shower that has a temperature above our family’s desired temperature of 113° F.  Since this is with an unusually high flow rate (that is, we have an older shower head) the T-K1 will have no trouble delivering sufficient hot water with a standard 2.5 gpm shower head.

    As you can see in the worksheet snippet below, the AquaStar 125 models do not deliver sufficient hot water for a 2.5 gpm shower; for our family’s 113° F. requirement (although it comes very close, probably close enough for other families' needs).

    Only the AquaStar 240FX (which is actually a Takagi T-K1) delivers enough hot water for our family.  The Takagi T-K2, a more powerful unit than the T-K1 is also suitable.

    My Recommendation

    For whole house use, where you expect to be able to have a shower without purchasing a super-saver shower head, use either a Takagi T-K1 or Takagi T-K2.  For any other unit, use the temperature calculator to determine if it will meet your requirements.  Many home owners, especially those who have installed super-saver shower heads, will find the Bosch 125FX to be sufficient to meet their needs, but it is vital that each purchaser take 15 minutes, perform the measurements, and satisfy themselves that the particular unit they are considering will satisfy their requirements.

    Availability In Canada

    In Canada, tankless water heaters are a niche product.  They do not have sufficient sales to have captured the attention of consumers.  In early 2002, here in Ottawa where I live, I was not able to find any contractor who would recommend a tankless water heater; however, I did find one Ottawa-based retailer who sells the AquaStar and Takagi units: The Fireplace Center & Patio Shop.

    Due to the low volume of product being sold, the Takagi T-K1, AquaStar 240FX,  and AquaStar 34B units are not imported by the Canadian distributor.  This low sales volume, and subsequent lack of competition in the marketplace, means that prices are high; too high.  In March 2002, I was quoted $3,700 to $3,400 Canadian dollars for a Takagi T-K2; whereas a price closer to $2,500 CAN should have been seen (the T-K2 can be purchased for $1150 US in the United States).

    Update: 2002-12

    Recently (i.e., starting in December, 2002) HomeDepot Canada has begun to sell the AquaStar 125 tankless heaters in Canada.  Many stores even have one or two units in stock.  The problem, as I have explained above, is that the AquaStar 125 may not be suitable for many whole home uses and so I expect consumers purchasing these units to be disappointed; which could lead to tankless water heaters being given a bad reputation in Canada.

    Update: 2003-11

    A few weeks ago I received a very helpful email from Greg McMurray from RCI Systems Inc. in Vancouver, B.C.  They are a distributor of Takagi water heaters in western Canada.  Greg reports that the tankless water heater market has taken off since I first composed this page.  As a result, Takagi has opened a Canadian office and the T-K2 our family was looking at can now be purchased for $1,800 CAN (plus shipping); which is a 50% reduction in the price.  Greg did admit that in most parts of Canada it is still tough finding local installation and service.  So, when our 5 year warranty expires on our current hot water tank, the industry should be mature enough for us to reconsider our tankless water heater purchase.

    How We Proceeded

    Although I believe the gas savings produced by a tankless water heater make it a good environmental choice, given the immature state of the Canadian market for tankless water heaters, we decided to purchase an inexpensive water heater tank with a 5 year guaranty.  In 5 years we will re-evaluate the availability of tankless water heaters and decide then how to proceed.   The main impetus for this decision was the poor availability and knowledge within the Ottawa HVAC service community: if the unit were to fail, getting it repaired in a timely manner would be extremely difficult.

    More Information

    Websites for more information about tankless hot water heaters:

  • Takagi Industrial Co. USA Inc. — the Takagi corporate USA website; the site it a bit broken (i.e., not all the links work) but does contain useful information, including installation manuals for their products
  • Low Energy Systems, Inc. — a commercial reseller of Takagi tankless water heaters, and it contains good technical information
  • Controlled Energy Corp. — a commercial reseller of AquaStar branded devices, and it contains good technical information
  • A Word About Venting

    With the advent of high efficiency appliances, venting exhaust gasses has become a little more complex.  As I've already mentioned, I am not a licensed HVAC tech. and the information contained herein should be verified by a qualified tech.; however, I trust these thoughts will help you to ask your contractor/installer the right questions.

    Things to think about w.r.t. the venting of gas appliances:

    May 2006 Update

    The topics discussed on this web page have always proven popular; however, in recent months the volume of emails and phone calls from readers looking for additional information has increased.  This short update is to attempt to answer the most common questions I am receiving, in the hope that readers will find what they are looking for here without the need for further digging.

    "Am I able to recommend a tankless water heater installer in Ottawa or Ontario?" --- The only company I know of in Ontario installing and servicing tankless water heaters is Day Energy Management in London, ON. There must be other companies performing these services, but no one else has ever provided me with a name, and I, myself, haven't yet needed to track one down. The one thing I suggest is that you contact the manufacturers of tankless water heaters and ask them for the installers they recommend.

    "Are you sure that you measured the temperature of your cold water properly; 39.2° F. seems too cold?" --- this question comes from people living in the south.  Here in Ottawa the ground freezes solid during the winter, and this means that the water pipes distributing water to our home get very cold.

    "Can you direct me to XXX manufacturer's website?" --- Here are the tankless water heater manufacturer websites that I am aware of (some info. scavanged myself, and some clipped from a September 2005 Enbridge press release):

    Manufacturer Contact Information
    Bosch www.boschhotwater.com
    Robert Jenkinson
    (416) 722-4399
    Noritz Brian Morgan
    (905) 477-9332
    MITS Airconditioning Inc.
    (905) 564-2221
    Rinnai Glorie Gale
    (905) 602-4588
    Takagi Steve Bagshaw
    (877) 877-4953
    Waiwela Yuri Fedoulov

    October 2006 Update

    Richard Dault emailed me to say that there is now a Canadian company that sells and installs tankless hot water heaters: Ozz Corp.  In addition, Ozz Corp. will rent tankless host water heaters. Ozz Corp.'s representative in Ottawa is Harding Heating and Cooling.  As of October 2006, the monthly rental fee for a 10 year contract was $30.95; this is for a Rinnai heater.

    April 2007 Update

    Martin Cooper emailed me to point out that potential tankless water heater purchasers should be aware that the flow of hot water from a tankless system differs from a traditional (to North America) hot water tank:

    The reason you should be aware of this difference is for situations where the hot water has already been running, and you restart the hot water.  In this restart situation you receive that plug of cold water in the middle of the hot water flow and it may catch you by surprise.

    ©Copyright 2002, 2003, 2006, 2007 Christopher & Jean Rath
    Telephone: 613-824-4584
    Address: 1371 Major Rd., Ottawa, ON, Canada K1E 1H3
    Last updated: 2015/02/14 @ 21:33:58 ( )