No hot water at home unless you turn on two hot taps/showers

Forums › Home Workshop DIY › No hot water at home unless you turn on two hot taps/showers

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blachel

10 posts

Wannabe Geek

#1078769 2-Jul-2014 16:58

Thanks Andrew,

I don't think the black one below the silver valve is a temperature ragulator. It spins freely and makes noise when I spin it with a tap on, thats why I thought it had something to do with presure.

andrewNZ: FYI, the bulky component on the incoming pipe (centre of the third photo) is the Ajax valve. It regulates the incoming water pressure.
If you adjust this valve one of two things happens.

Your hot water pressure gets worse
You overflow the hot water onto your roof constantly meaning you'll possibly have no hot water and a huge power bill.
The silver one is the tempering valve. It has hot water from the cylinder on one side, cold water from the supply at the bottom, and feeds the taps on the other side. The black valve below the tempering valve is probably a regulator to adjust the temperature at the tap.

I suppose there is a chance that the tempering regulator has been adjusted and is causing this. The way my mind sees it, it could fit your symptoms exactly. BUT, I'm not a plumber.

andrewNZ

2487 posts

Uber Geek
Inactive user

#1078772 2-Jul-2014 17:08

It's not a temperature regulator on it's own, but I think it will affect it. If you adjust the cold pressure to the tempering valve, it will ultimately affect how much it changes the temperature. High pressure forces more water through a hole than a lower pressure.

As you've already been messing with it, there's not a lot more harm to be done. So if you turn the black valve all the way on way (likely many turns) the hot water temperature at the tap should change.
My guess is clockwise will make it hotter, and anticlockwise might make it colder.
Keep in mind it takes time for a change to have an effect, the water has to get from the valve to the tap and heat the pipes too.

gzt

17127 posts

Uber Geek

Lifetime subscriber

#1078776 2-Jul-2014 17:11

Because you had leaks there is a very small chance this problem is the result of an unusual airlock condition which has not yet cleared. If so, it's easy to fix. Turn on all the taps in the house and wait 5 minutes. Run your combined hot/cold taps on warm.

This one costs nothing and does not require any modifications to the system. ; )

Bung

6485 posts

Uber Geek

Subscriber

#1078805 2-Jul-2014 18:20

The black valve at the bottom is the cold water expansion valve. As the water in the tank expands you lose colder water from the bottom of the tank rather than hot water from the top.

NonprayingMantis

6434 posts

Uber Geek

#1078807 2-Jul-2014 18:24

hmmm, seems like a config error to me.

I would suggest a factory reset of your house. That should clear the cache and allow the hot water to flow properly.

If the error keeps coming back though, your processor (food processor of course) might be fried and you'll need to replace that.

Have your tried turning it off and on again?

blachel

10 posts

Wannabe Geek

#1079105 3-Jul-2014 08:53

kiwitrc: It might be a sticky tempering valve, you will see this near the HWC it has hot in one side and cold in the other, it mixes the two to a lower (safe temperature) You could try running a tap and giving the valve a firm tap or two to see if the hot then starts to flow from the tap. I would have thought a plumber would have thought to check this.

I have tapped the temering valve yesterday while have a tap on. I noticed that this morning, the water came though the tap in the bathroom is hotter than normal but not as hot as it could get. However, it was still cold from the kitchen tap. (the cylinder is located closer to the bathroom compared with the kitchen. I had the kitchen tap on for like 1 min only. I'm not sure if it is just a matter of time to get the hot water through.)

blachel

10 posts

Wannabe Geek

#1079107 3-Jul-2014 08:53

gzt: Because you had leaks there is a very small chance this problem is the result of an unusual airlock condition which has not yet cleared. If so, it's easy to fix. Turn on all the taps in the house and wait 5 minutes. Run your combined hot/cold taps on warm.

This one costs nothing and does not require any modifications to the system. ; )

I'll try this tonight. Thanks gzt.

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blachel

10 posts

Wannabe Geek

#1079756 4-Jul-2014 09:08

gzt: Because you had leaks there is a very small chance this problem is the result of an unusual airlock condition which has not yet cleared. If so, it's easy to fix. Turn on all the taps in the house and wait 5 minutes. Run your combined hot/cold taps on warm.

This one costs nothing and does not require any modifications to the system. ; )

tried this but it didn't fix the problem...still won't get hot water with on tap on only...

kiwitrc

4123 posts

Uber Geek
Inactive user

#1079778 4-Jul-2014 09:31

Maybe its time to call a plumber

Aredwood

3885 posts

Uber Geek

#1081278 5-Jul-2014 01:23

That tempering valve will be stuffed. The Version you have (early Nefa / HMC) is the worst one for faults. Problem is the better ones have a different pipe layout. The cold and outlet connections have been swapped. Often the easiest method is just remove the tempering valve. Connect the hot and outlet pipes together. And put a cap on the cold pipe.

gzt

17127 posts

Uber Geek

Lifetime subscriber

#1081437 5-Jul-2014 12:53

Definitely call a plumber. Maybe not the same one you used previously. Either there were communication problems about this issue or that guy was not a very good plumber.

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