Hot Water tempering Valve.
 (Tricks of the trade)

Fred was "our" plumber for about 20 years until he passed away. He was a lovely person always cheerful and a great and fair tradesman who had a long list of regular customers built up by word of mouth.

Recently on a TV medical show there was a case of a 90 year old who was scalded. He was a cheerful old chap but unfortunately his burns lead to his death. We occasionally have the grand kids over and my wife blindness means that a hot water accident was waiting to happen. 

I decided to have a water tempering valve fitted.  These valves adjust the temperature of the water by automatically mixing the correct amount of hot with the cold back near the hot water system and maintain a set temperature for the outlet water. This tempered water is piped to the areas where accidents most often happen ie. the bathrooms. The kitchen needs direct hot water if you want to abide by health department requirements for washing dishes.

When I told a mate about the fitting of a tempering valve he said he had pulled his out as he liked hot water. I thought no more about it until the water heater needed replacing and the young plumber asked if I wanted the tempering valve removed. When asked he said lots of people have them removed. I can only surmise that they do this because there has been some sort of failure. Perhaps the hot water inlet filter to the valve has become clogged. With my valve set to deliver 48C water I still find that a little cold has to be added for comfort when showering. Perhaps the valves are being removed because there is no proper hot water to the kitchen sink for dish washing.

Finding a plumber and buying the valve.

I started asking around. A couple of recommendations never returned my calls. Finally I had some "luck" and made contact with a plumber who was a friend of a friend.
I looked up on the Internet and found the price of a water tempering valve was $147 I then rang a discount shop and was quoted $127.  The plumber came over, took a look at what was needed and gave me a contact to buy the valve which I did at the great price of  $78. As he was leaving he said that I should not expect that the job would cost $100 or so as he charged $75 per hour. That was no problem I said after all he was a friend of a friend.

I have had a few people contact me about the low cost of the valve.
If you have solar or instantaneous hot water you will need a high performance valve that will cost about 50% more than a standard valve.
The valves come in nominal 1/2 and 3/4 inch sizes with matching prices. I believe that most houses use the smaller size. My house has 1/2 inch hot water pipes and 2 bathrooms and used the 1/2 inch size.

The Job.

Water tempering ValveOriginally the hot water outlet at the top of the water heater lead to the green pipe now connected to the middle of the valve and after two bends lead under the house. The house has good access underneath.
The pipe from the "T" at the top now connects hot water to the kitchen. The pipe from the middle of the valve connects into the old hot water supply line and provides tempered water to the rest of the house. The cold water to the valve enters from the bottom and is drawn from the cold supply with a "T" in the inlet pipe just visible at the bottom of the picture. The kitchen is about 1.4m away and the total length of pipe used was about 4.8m.

The valve came with fittings but 2 "T" and 2 unions were needed as were a couple of joiners under the house.

Gas cook top connection.

The gas cook top was on its last legs and I managed to get a new one in installed in time for the plumber to connect it. This required the plumber to supply a short length of pipe and 5 fittings (4 of which were new). the new regulator and the other fittings came with the stove and the tap was already there. the plumber scored the old regulator with it's attached 3 fittings.

The result.
The water to the bathrooms and laundry was tempered to 50C. This we still felt was a little hot and was easily adjusted down by use of the yellow cap on the valve. The plumber commented that the AVG brand model TVA 20-15 tempering valve was of better quality than the usual one he fitted. The plumber had worked steadily for the almost 4 hours he was there. I said I would cover the hot pipes with the left over insulation. The stove worked as expected

The Bill.

Pipe and fittings   $110.00
Oxy-gas + Silver     $60.00
Service Call         $75.00
Labour $75 X 4    = $300.00
SUB TOTAL           $545.00
GST                  $54.50
TOTAL               $599.50
I gave him a 50c tip

What I have learned
I estimated the required time correctly  but you may like to ask for an estimate.

Ask about the call fee as even a friend of a friend who had to stop nearby to drop off his wife charged me one.

Ask if they are going to load the bill with extras like gas and silver and how much.

Get an estimate for pipe and fittings.

Find out if all the above are going to have GST added on to them.

To quote Meany George "Anybody who has any doubt about the ingenuity and resourcefluuness of a plumber never got a bill from one"

Insulate the water piping (cold inlet and hot outlet. Not the pressure release valve or pipe) near the heater.  If the inlet or outlet pipe feels hot when the tank has not delivered hot water then you are wasting money, at a guess $10 PA which can mean you have banked $150 when it it time for a new heater.  I used some plastic bubble wrap covered with weatherproof plastic tape.