How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manufactured and modular homes
Why should a tankless water heater have an isolator/service valve kit installed?
Thursday, June 21, 2018
Manufacturers call it an “isolator valve kit” or “service valve kit,” and plumbers often just say “flush kit.” It’s a set of four valves, two each on the hot and cold water pipes below a tankless water heater, that enables you or a service person to flush out any mineral scale buildup inside. The bottom two valves disconnect it from the house plumbing system and the top two valves open the pipes to threaded front hose connections for recirculating vinegar through the water heater to dissolve the scale buildup.
“It’s real easy to tell if you have one,” according to Jimmy at J W Freeman Plumbing. “Look for four valves right below the water heater.” They are usually color-coded red and blue for the hot and cold water sides of the system, like in the photo above. Some manufacturers include the valve kit with the water heater, while others sell it separately. As far as we know, they are not required by the building code.
Having a service valve kit is important because you cannot flush the system without one and, if you have a problem with your water heater after several years and call the manufacturer for warranty service, they won’t honor the warranty unless the system has been flushed. Flushing the system annually is necessary if you have very hard water, but can be done less often otherwise.
The valves are the first part of what you need to flush the system. A large bucket, hoses, and a sump pump are also necessary to circulate several gallons of vinegar through the water heater for about an hour to clean it out. You can buy the other items yourself, but plumbers have the additional equipment for a flush if you call one for service—except that they can’t do it without a service valve kit in place. An example of a tankless gas water heater without a kit installed is shown below.
If the bottom of your new tankless water heater looks like this, you can expect to have problems after three or four years that neither the manufacturer’s or builder’s warranties will address.
• • • • • • • • • • • • • • • • • • • • • • • • • • • •
Here’s links to a collection of more blog posts about WATER HEATERS:
• • • • • • • • • • • • • • • • • • • • •
Field Guide for Home Inspectors, a quick reference for finding the age of 154 brands of HVAC systems, water heaters, and electrical panels, plus 210 code standards for site-built and manufactured homes, and the life expectancy rating of 195 home components. Available at amazon.com for $19.95.
• • • • • • • • • • • • • • • • • • • • • •
of Blog Posts
Top 5 results given instantly.
Click on magnifying glass
for all search results.
Buying a home in North/Central Florida? for a team inspection by two FL-licensed contractors and inspectors. Over 8,500 inspections completed in 20+ years. In a hurry? We will get it done for you.