Rheem 325 II Series Service Instructions Manual page 28

Excessive hot water usage – 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.
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 comparing this with the
potential delivery of the model of 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 and excessive pressure relief valve discharge
6. Plumbing leaks
7. Crossed connections
Water hammer – A water heater will not cause water hammer, however valves associated
with the water heater may be the source of the problem. For example, a cold water
stopcock, non return valve or relief valve.
Most water hammer problems are associated with hot and cold water plumbing, or
appliances. For example, solenoid valves, ballcocks, loose pipes, sharp angles in
pipework, 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 the 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 storage tank, 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.
TM077: 325 & 410 Series II Heat Pump Service Instructions
Rev 00: Issued April 2014
This document is stored and maintained electronically by Service. All printed copies are deemed uncontrolled.
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