Ask Me Help Desk - Tankless water heater

I want to convert from a (gas) tank water heater to a gas tankless water heater. When I called a local plumbing company for a bid, I was told prior to installing the tankless heater it is necessary to replace all plumbing in the house. This would involve ripping open the dry wall in several rooms, destroying a expensive ceramic tile floor and jackhammering the concrete pad upon which my house sits. Is this demand as insane as it seems? The house was built in the early 1970's and has 1/2 inch copper water lines.

They want to repipe your house to install a water heater? I sure would like to hear the reasons and sales pitch they gave you along with all that smoke they were blowing. Unless you have aggressive water or electrolysis your copper pipes should be just fine and I've water pipes hundreds of houses and condos in copper even before the 70's. Did they say what they wanted to repipe you with? Regards, Tom PS. Did they tell you what part of the Caribbean vacation spot they were headed for as soon as you paid them??

Time for the three bid rule to be invoked. Somebody is try to make a fortune here. Be careful when you select a on demand heater. Many were recently recalled, I think all were 199,000 BTU models. By the way, I hope your house is not entirely 1/2" copper, aren't there some larger runs with 1/2" branches?

The only repipe you should need for a tankless water heater is the gas supply line. A typical tank heater needs a 1/2" gas line, while a tankless needs a 1" or larger depending on the distance to your meter. There are no compromises here, trust me, I tried it, it was completely unsatisfactory.

Unless your water pressure at the fixtures is really poor, nothing else matters. You need about .75gpm at the fixture to turn on the heater (like a bathroom sink with aerator on full).

Quote:

Originally Posted by Desert Runner

I want to convert from a (gas) tank water heater to a gas tankless water heater. When I called a local plumbing company for a bid, I was told prior to installing the tankless heater it is necessary to replace all plumbing in the house. This would involve ripping open the dry wall in several rooms, destroying a expensive ceramic tile floor and jackhammering the concrete pad upon which my house sits. Is this demand as insane as it seems? The house was built in the early 1970's and has 1/2 inch copper water lines.

I'm not trying to pee in your cornflakes, Dessert Runner, but I noticed you didn't answer Tom's question about the reasons given by the Plumber for recommending a total re-pipe.

Did the Plumber point out that it was common practice in the era your house was built in to use 50/50 solder on copper water piping (50% tin and 50% lead)?

Did the Plumber point out that we have discovered in the intervening years that the lime in concrete and thinset will react adversely to copper piping and the 50/50 solder used on the joints?

It's a tough call, but given your limited description of the existing installation conditions I might very well have recommended a re-pipe as well.

Kids would have been another factor -- If I'd noted you have children while doing the walk-through, I would have explained the potential hazards of lead exposure to children as well.

Y'know, it's possible you were being scammed, but we can't really say that's the case if you don't tell us why the Plumber made the recommendations he made.

Thank you for your response. I was aware that the gas line would need to be changed and water pressure at all faucets (indoors and outdoors) is quite adequate.

In response to your comments, at this point 5 plumbing companies have been contacted. A current state license and good ratings at BBB, Angie's List, or other such venue were all verified prior to contact.
1) The first company was responsible for my question. In the initial phone conversation, the company representative told me that my entire house had to be re-plumbed prior to installing a tankless water heater. It was also stipulated that the job would take 3-4 weeks. All furniture and possessions had to be removed from the house as the company could not be responsible for theft from an unsecured job site. I, the property owner, would also be barred from the property for the duration of the job as the company’s insurance would not cover any injury I might sustain while on the job site. This company has never been on my property and I guarantee they won’t get the job with these demands.
2) Three companies came to my house, looked around and gave me verbal estimates. When I requested a written estimate, all three declined.
3) Only one company provided a written estimate. And yes, iamgrowler, this plumber did mention the 50/50 solder and corrosive potential of lime in water & concrete. He did not think either would be a problem. This plumber was also the only one to actually take out a tape measure to verify that clearance distances specified by code could be met.

Thank you for your thoughtful and insightful answers.

That is bad advice. You do need a fairly large gas supply line to your tankless water heater, because it burns hard and intense when it is on. But hot water is hot water once it leaves the heater. There are a lot of baloney rules and regs, so maybe where you live the government is saving you from yourself. Get referred to a plumber that has installed them in the past and likes them. I switched from standard electric water heater to tankless gas 10 years ago. Love it. No regrets. But it produces lime that looks like sand in my hot water lines and it builds up in shower heads, screens on clothes washer, etc.