My current tankless, instantaneous gas water heater is placed in a location where pipes in and out of it are 3/4''.

I was planning to remove it and install an electrical, tanked water heater, in a different location, where a shower used to be. When starting the work, I actually realized that the pipes there were 1/2 ''.

Is that likely an issue in terms of having enough hot water at the other end of the house for showers? The distance between this electrical water heater and the furthest shower would be about 15 meters (49 feet).

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    Nobody ever complained about water pipes in a house "too large and flowing too much" I personally wouldn't do this you are going backwards IMHO. I'd put a nice gas water heater in instead of the instant thing. But I'm old school. Are these pipes copper or galvanized? Feb 24, 2021 at 8:53
  • @TedMittelstaedt the pipes are thick plastic. The problem is that the current location is tight (in a small cupboard), so I cannot put a tanked water heater.
    – DevShark
    Feb 24, 2021 at 9:01
  • PROBABLY it will work. Ideally you feed 3/4 from the main coming in to a split one side that feeds the hot water heater which then feeds the rest of the hot pipes, the other side feeds cold water. The distribution pipe is 3/4 the laterals are 1/2 But I have seen it all 1/2 even 1/2 coming in from the street. Unlike galvanized plastic won't restrict flow down as the inside of the pipe rusts. Feb 24, 2021 at 9:10
  • It seems that going from a gas heater to an electric one is a step backwards, too, from everything I've read here. The electric ones seem to be much less efficient and you may end up with quite a shock (pun intended) from your next electric bill.
    – FreeMan
    Feb 24, 2021 at 12:57
  • I have installed both versions of tanked and tankless water heaters (and heat pump water heaters) with electric tanked the recovery time is longer and annual cost is higher than a gas tanked heater although that may change with the current administration. If going to electric investigate the pros and cons of electric heat pump. Some power company’s have rebates that almost cover the purchase price.
    – Ed Beal
    Feb 24, 2021 at 14:51

1 Answer 1


Whether the 1/2" dia pipe will provide sufficient flow depends on your requirements. Personally I would use it. The flow would supply any ordinary single shower head. I would recommend a hand holdable, low flow shower head with a flexible hose rated at say 1.5 gal/min (5 to 6 L/min). This would save energy and water while giving a fully adequate shower.

The 1/2" dia pipe will mean that hot water from the heater will arrive at the shower quicker than with 3/4" pipe. There will also be less water wasted and less hot water wasted by abandonment in the line.

  • Agree completely! Great answer, I was about to say the same thing. The smaller pipe holds a lot less water so it will get hot much more quickly. Glad you mentioned it. Feb 24, 2021 at 15:00

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