Weird HW Issue...

All input appreciated!

I have an old Colonial and from what I've seen renovating the place over the last year, everything was well done for it's time. I recently yanked an oil-fired hot water heater and replaced it with an electric. I did this all to code with a new 220/etc. The hot water has been operating wonderfully for about 6 months.

Here's the weirdness. There's a HW branch in the basement that goes off into a small first floor addition where there's a washing machine, 1/2 bathroom, and outside spigot. There's a level valve to turn off the HW to this branch.

Now when I leave said level open, hot water runs throughout the addition. Cold water comes out the sink on the cold water feed, hot water comes out the hot water feed. The outside sigot gets 'warm' water- so does the toilet. But the rest of the house that is after the branch gets luke-warm hot water (cold water fine).

When I have the valve closed, hot water is fine to the rest of the house. The addition gets COLD water through the hot water feeds.

I've never installed a mixer- but I'm thinking there's one in the addtion that may have been added to prevent pipes from freezing due to the limited warm air getting under the addtion.

Am I on the right path?

Could be from the washing machine connection...

There is a cross connection somewhere...
Isolate it by turning off all the angle stops and then turning them on one set at a time until the problem reappears...
The set you have just turned on will be the culprit...
Could be the washer as mentioned...

I just replaced the mixing valve on our washing machine for only about $15 bucks. Easy job.
Mike

valve

It is not a "mixing valve". It just sends the hot and cold water to the same outlet. But there is no pressurized connection between them, so the washing machine valve cannot cause the problem. We might have to see a picture of how the connection and valve are arranged.