So I just got out of interesting meeting with a potential client and the discussion came up about tankless hot water heaters and are they always the best solution to any given situation? Simple answer is NO! There never is “a” best solution to any given situation.
Water heater replacement just like anything in energy efficient construction and building should be looked at as a whole systems approach. Let’s say you have an old tank heater that needs to get replaced, here are the important things to consider:
- Is it electric or gas?
- If it is electric, is there a gas line nearby and will it be easy to install a vent pipe?
- Where is is located? Is it more than 10 feet away from the source and does it serve sources that are located in different parts of the house?
- If it is far from the source, can it be relocated to get it closer?
- Are the sources spread out all over the house? (kitchen on one end, master bath on the other and guest bath over the garage….)
Answer those questions for yourself and you can come up with a good solution:
- If it is gas, stick with gas and install a tankless gas heater
- If your answer to question 2 is yes and yes, make the switch and install a gas heater
- If your answer is yes, consider decentralizing your water heating system and install multiple smaller heaters to reduce your pipe runs from the heater to the source
- If your current water heater location is pulling water from one end of the house to the other, consider moving the location of the water heater as close to the source as you can.
- If your sources are spread out, you might be best served with 3-4 smaller electric heaters that can be installed under cabinets or in small closets. This is of course if your electrical service is adequate.
Just like anything else in a green building or remodeling project, you have to look at the whole picture – especially when it comes to the electric vs gas debate.. and btw – do not listen to your plumbers opinion, because it will always be gas. If you are remodeling your entire house, replacing plumbing, upgrading your electrical service and have the luxury of deciding exactly where your water heaters are going to be located, electric water heaters have some benefits:
- Less expensive in initial purchase price
- No gas lines to run
- No exhaust venting and addtl wall/roof penetrations
Now the bad:
- The good ones draw quite a bit of power – anywhere from 80-120 Amps – this means if you have 3 of them you need a quite sizable electrical service which can get costly if you’re not already upgrading your service anyway
- Flow-rate – even the best electrical tankless hot water heaters have an inferior flow-rate to their gas counterparts which means you have to be very careful and thoughtful during the planning phase.
So when it comes time to replace your old water heater, you have to consider much more than just the actual piece of equipment. And that’s where we come in. EGC specializes in building energy efficient, comfortable and healthy homes. Your path to energy efficiency can start with replacing your water heater, but you have to do it right.
We are huge advocates of decentralized systems – gas or electric – because to us, the most efficient system is the one that wastes the least amount of water and has the least amount of heat loss from heater to source. How many gallons of cold water do you run down the drain each morning before your water gets hot ??
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It seems to me a contradictory that on one hand you indicate not to generalize what water heater solution would be best in every situation, yet you generalize “not to listen to your plumbers opinion, because they will always recommend gas”.
As a plumbing contractor for over 30 years, an instructor for almost as long and now working for greenplumbersusa I have learned, as you have stated, that one solution to differing situations is not the answer.
I also know that there are ‘enlightened’ plumbers who do know quite a bit about electric tank and tankless type water heaters. You should not generalize.
About electric heaters: While the initial cost is somewhat lower, a standard tank type electric heater will recover at less than 1/2 the hourly rate of a gas heater and usually at least twice the cost per gallon. Tankless electric water heaters work on as little as 30 kWh
As far as hot water distribution is concerned we teach:
1. Improve the Use
2. Reduce the Waste
3. Increase the Efficiency
4. Increasing the efficiency is NOT solely the function of the water heater or the piping system. Flow rates, Delivery times and Individual behaviors play just as big a role
8 truths about water heaters:
All storage type water heaters lose energy in the “standby mode” through the sidewalls and top of the tank even though they are insulated.
A typical gas fired storage water heater also loses energy from the center of the tank through the flue.
*Tankless water heaters can save energy by minimizing standby losses.
*Tankless water heaters can provide an almost unlimited supply of hot water, but do not get heated water to a fixture faster than storage water heaters.
*Tankless water heaters may increase water consumption.
*Tankless water heaters may increase energy consumption.
Minimizing the pipe size and length will reduce energy loses for any hot water system.
Locating the water heater as close to the the demand as possible and insulating the piping adds to the reduction.
*As it relates to tankless water heaters: You have to start with what is the motivation for installing a tankless heater? The potential is there to save energy if the users behaviors remain unchanged. If the users behavior remain unchanged water use will remain unchanged (there will be no water savings and in fact, water use will be slightly increased because there is a no hot water to deliver for several seconds after there is a demand).
If, on the other hand the user’s behaviors does change, because there is now a continuous supply of hot water and they or some other user on the property take advantage of it, both energy and water use will increase.
Doug;
, but at the same time I walk into a lot of situations where clients where sold on new water heaters and the system that was sold to them does not work because it was not the right solution to their problem. Again thx for your contribution and keep them coming.
Thank you for your comment and additional contribution to my post. You are correct, I should not generalize but the fact is that about 90% of the times, plumbing contractors will recommend what they are most comfortable installing, not what might be best for the situation. I know that there are great plumbing contractors out there that are highly educated in their field (I happen to work with a couple of them
Excellent! Great article, I already saved it to my favourite,