Question: We had a gas high-efficiency furnace installed in our 1991 built, one-storey house, about eight years ago. Seven years ago, our gas water heater was changed, with no modifications made to the chimney. I heard that a chimney liner is now required before a new gas hot water heater can be installed. Is this correct? Is there an alternative? Who should do this work and do you know an approximate cost?
Is it better to switch to an electric water heater, as this conversion requires new electrical work? As far as gas versus electric, what is the payback over time?
Answer: Switching to an electric water heater, after you have upgraded to a high-efficiency furnace, makes sense for several reasons. Overall, the slightly higher costs over the lifetime of the unit will depend on several variables, but should not be the main criteria for this upgrade decision.
The first thing I would like to address is the information you have received about the need to upgrade the metal chimney liner when you replace a natural gas-fired water heater. This may be a requirement if your current liner is improperly sized, corroded, or none is installed. Since your house is relatively modern, the chimney will undoubtedly have a metal liner, or will be a B-vent surrounded by a constructed chase. The issue with the current liner may be that it was properly sized to handle both the old furnace and water heater flue gases. Since the furnace no longer vents through this metal piping, it may be considered too large for only the water heater. If that is the case, any gasfitter replacing your current water heater may be required to install the properly sized liner to accommodate only that unit, regardless of the condition. This may have also been the case seven years ago, but was not enforced by the local building inspector.
The National Building Code (NBC) is the document that makes recommendations for most forms of construction in Canada. There are several parts, which are regularly reviewed and modified to adapt to changes in construction materials, techniques, and building science. The thing most misunderstood about the NBC, by many homeowners, is that following its guidelines isnt mandatory. Adoption of the NBC, either in its entirety or various portions, is at the discretion of the local municipality that regulates construction in a certain area. Also, the building officials for each area under its jurisdiction may further decide to apply or waive various portion of the codes, as they see fit, to adapt to varying conditions in different locations. So, the only way to verify or rebut that statement is to contact the local building officials in your area for their current requirements.
As for changing your water heater to an electric unit when your current one fails, that should be much more straight forward. The negative aspects of switching to heating your water with electricity can be summed up in three segments. Firstly, it takes longer for the water to reheat in an electric tank, once emptied, than gas-fired units. This is normally solved by installing a larger sized tank, which prevents running out of hot water. Secondly, your electrical service must be large enough to accommodate adding the circuit breaker for the new unit. This should be no problem for a home of your age, but will add a cost for the technician or electrician to install the breaker and wiring. Finally, it currently is more costly to heat your water with electricity than with natural gas, which will depend on fluctuating utility rates.
The pros for switching to an electric model are more numerous, and in my opinion, outweigh the cons. No. 1, the current chimney will no long be needed and can be sealed top and bottom and largely forgotten. This will prevent repairs due to a damaged liner, leakage, or other maintenance issues. In some cases, the chimney may be completely removed and the roof patched and shingled over the old opening. This will provide one less item to maintain, and potentially save money in the long term. For sure, it will make the question of changing the liner a moot point.
The second benefit of installing an electric hot water tank is due to the longevity and lack of maintenance. These units are less costly to purchase and will have a longer life expectancy than the average gas-fired units, typically 25 to 50 per cent. Also, there is almost no maintenance or inspection required for the lifetime of most electric units, contrasting with gas heaters. Any gas-fired appliance is more likely to have a failure. This could be in the gas valve, supply piping, vent pipes, thermocouple, or other components related to the delivery and combustion of the fuel. Any problems with these issues can be a major life-safety hazard and will be an added cost to repair by a licensed gasfitter.
The last plus for electric water heater replacement may be more intangible, which is the environmental advantages. Heating your water with electricity, at least in most areas of our province, will have minimal carbon output compared to a gas-fired unit. Since the majority of our power comes from Hydro generating stations, the emission of greenhouse gas is almost nil. So, changing from natural gas to electric will be one small step in the goal of reaching a carbon-neutral future.
Changing your current natural gas-fired water heater to an electric unit, once it reaches the end of its serviceable life, has several benefits which are not all economic. Choosing an upgrade that lasts longer, requires less maintenance, and is more environmentally friendly, may outweigh the slightly higher overall costs.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and a Registered Home Inspector (RHI)(cahpi.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at trainedeye.ca.