TM017 Rheem Air Sourced Heat Pump Service Instructions REV: C
Date of Issue: 5/11/05
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7
Excessive hot water usage
- The complaints of insufficient hot water and no hot water
can on many occasions be attributed to hot water usage exceeding the capacity of the
water heater to provide hot water.
When first attending a call of this nature it is essential to establish the probable hot water
usage by querying the usage habits of the household and compare this with the potential
delivery of the model water heater installed. It can then be established if the usage is
within or outside the capacity of the model. The areas to look at for excessive usage are:
1. Automatic washing machines.
2. Showers exceeding 12 litres/minute for mixed water and 5 minutes in duration.
3. Two or more showers operating at the same time.
4. Change of occupancy or number of persons increased.
5. High water pressure area. (Excessive pressure relief valve discharge)
6. Plumbing leaks
7. Crossed connection
Water hammer
- A water heater will not cause water hammer, however valves associated
with the water heater may be the source of the problem i.e. cold-water stopcock, non-
return valve or relief valve.
Most water hammer problems are associated with plumbing, hot and cold or appliances
i.e. solenoid valves, ballcocks, loose pipes, sharp angles in pipe work, faulty or worn valve
parts, loose tap washers or neighbouring equipment.
High water pressure areas will have more complaints of this nature and the use of a
pressure-limiting valve (PLV) to reduce the household cold-water pressure will usually
solve most problems.
Hot water plumbing leaks
- If hot water has not been used for a period of time, feeling
the temperature of the hot water line may give an indication of water flow if the pipe is
warm. The method of checking for plumbing leaks is:
1. Turn off the stopcock on the cold water supply to the water heater.
2. Open a hot tap to ensure the flow of water stops. This will confirm the stopcock is
operating correctly.
3. Turn off the hot tap.
4. Turn on the stopcock to make up the water pressure in the cylinder, and then turn the
stopcock off again.
5. Wait approximately 5 minutes then do either of the following:
a. With your ear close to the stopcock turn it on slightly and listen for any water
passing. If there are no leaks, water should not pass.
b. Open a hot tap while listening for any pressure release. If there is a pressure
release there will be no leaks in the plumbing system.
Mixing or crossed connections
- If an automatic dishwasher, washing machine, flick
mixer tap, tempering valve or thermostatic mixing valve is installed there is always the
possibility that the cold water could mix with the hot water through a faulty or incorrectly
installed valve. This is referred to as a cross connection. The complaints of insufficient hot
water, water too cold or excessive discharge from the pressure relief valve may be
attributed to a cross connection. The method of checking for a cross connection is:
1. Turn off the stopcock on the cold water supply to the water heater.
2. Open a hot tap. If water flow is persistent and cold a cross connection exists.