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 48°C
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.
Originally 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
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.
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
50°C. 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
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
$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.