Critical article on Tankless water heaters

Paul Pollets

Thanks for the article, Dan. As I suspected, the efficiency ratings were overstated by the manufacturers, just like AFUE. While the research did not address their use in combined heating/DHW systems, I'm more than convinced that these appliances are a poor choice for DHW usage except in small homes or apartments. They are simply dangerous when used for both hydronic heating and DHW and should be removed as "acceptable" from the codes. That includes the state of Washington, where I live.

Ironman

Paul

Can you post a link to the article?



Thanks

STEVEusaPA

I think he was referring to Dan's newsletter.

http://www.greenbuildingadvisor.com/blogs/dept/musings/are-tankless-water-heaters-waste-money?lookup=auto&V27=R&V28=5&V29=10&V30=N&V31=&V32=0&V33=0&V34=0&V35=0&V55=01-JAN-2013&V56=0&Taun_Per_Flag=True&utm_source=email&utm_medium=eletter&utm_term=water-heating&utm_content=20120416-concrete-countertops&utm_campaign=fine-homebuilding-eletter&utm_source=May+3%2C+2012&utm_campaign=Email+Newsletter+Analytics&utm_medium=email

DanHolohan

On the home page

There is an envelope icon off to the right. Click it and get on my List for the Thursday e-newsletter. It's free and I send articles like that one to more than 5,000 subscribers each week.

CMadatMe

Very Powerful

Study was very powerful and opened my eyes to quite a bit of the marketing ploys from the tankless manufactueres. I'd love to see the same study as to the comparison of a tankless combi and a condensing boiler with indirect.



This is definiately a study where experts can be used to educate a consumer.

bob eck

Tankless gas water heaters

I am a salesman for a P&H wholesaler and when I talk to contractors about TGWH I do not push the energy saving like all the TGWH manufactuers do. I tell contractors that home owners can take shower after shower after shower and never run out of hot water. TGWH are expensive to install in retro fit jobs because of venting plus upgrading the gas line to a larger size. If home owners are running out of hot water I would check their shower heads to see how many GPM is coming out of them. Reducing 2.5 GPM shower heads down to 1.5 GPM makes a big difference. Delta has a great 1.5 GPM shower head. If there is a tank type water heater you can store the water at a higher temp and use a mixing valve at the water heater. The life of a tankless gas water heater should be 20 years or so. How much maintenance will be needed in 20 years of use. Tank type water heater life could be 10 to 15 years or more if flushed out often and if anode rode is changed every two to three years. In today's tough economy I believe most contractors need to get as many jobs as possible and you have to work hard and sell the home owner to go tankless and most home owners are looking for a competitive water heater installed and most replacement water heater jobs are when the old water heater died and they need want hot water now. Just my thoughts

TonyS

Not many of the homes built

in the last decade had chimneys(at least in our area) and were fitted with a 40 gallon power vent. Now the pricing gets alot closer and The warranty on the Navien and the Eternal are more than double that of a typical power vent.  No doubt its a stretch on payback with natural gas... NOW. Most of my tankles go in the country where the cost of propane really magnifies the savings. Another article filled with half truths.

TonyS

As far as dangerous goes

I think any gas appliance that is not two pipe should be made illegal. The air you breath in your home should have nothing to do with air that supports the combustion of your appliances! With the windows and sealants today coupled with bathroom vents, whole house fans, stove vents, driers ect.

its hard to believe this type of equipment is still made.

SWEI

appropriate use

Tankless water heaters make a lot of sense for some very specific applications.  Selling them as the be-all and end-all of efficiency is just garden variety greenwashing IMO.

Jack

Another tool in the tool bag...

As you know, I've been affiliated with Rinnai for about 22 great years. Although no longer their manuf representative I am working with them on a consulting basis here in the CA market. My support of tankless is not deterred by this report in the least.



Tankless manuf did not develop the EF flow tests. As a result they are not using a "ploy" to pull the wool over your eyes. They were granted, they earned, these EF's based upon the test they had to meet. This report was based upon other data and I'd expect it to have different results. From a .82 EF to the .70 represents a 12% reduction. .61 to .49 represents a 20% reduction. Regardless of anything else it is difficult for me to think the industry embraces anything that is .49.



Currently we are looking at the lowest NG costs we have seen in a very long time due to an "overproduction" of NG. We have developed methods of extraction that I think will have a very long tail and expense related to pollution of ground water, but, hey, gas is cheap. I'm a tad cynical about these issues as I remember when I was a kid in grade school where we were told that we had so much oil we wouldn't be able to pump it all. As well, back in those days the word was that with nuclear, power would be so cheap you wouldn't even have to meter it! How'd that work out? We are enjoying the cheap NG glow right now, but do you really think it will last and do you want to support energy products that get us all the way up to .49EF?



Years ago Rinnai made a deal with the late, great Paul Harvey to promote tankless water heaters. This relationship was initiated by Mr Harvey. He had a tank water heater fail and damage was done to his home. He said to his plumber, "There has to be a better way"? After living with the Rinnai tankless for a while Mr Harvey requested a meeting with the head of Rinnai. In his meeting he said, "when I look at my energy savings with this tankless and look at the potential savings on a national basis this is good work to do". He also said, "I may be an old man, but I can still make tracks in the sand". And did he ever! This conversation was told to me by the representative from Rinnai who met with Mr Harvey.



I've lived with tankless for the past 14 years. I had one in my home for 11 years and changed it out when I remodeled. It was in fine condition but I knew I was going to be selling the house and it was a pre-production unit for test, so I had to put in a current approved model to sell the house. I didn't touch that water heater the entire time it was installed. With my Rinnai tankless my gas consumption went from 36-44 therms/mo to 10-13. Currently living in my new old house I am re-modeling the bathrooms and kitchen...as soon as the boss tells me what fixtures I'm using. Since moving into this house last summer I have had a tank water heater and frankly, I cannot wait to get rid of it. Two showers and you are bingo hot water. I'm going back to a tankless with a smile on my face and a song in my heart.



In the trades, you get to make choices on what you want to support. Tankless is or should be "another tool in the tool bag"