Expansion Control Valve (Ecv); Relief Valve Drain - Rheem 3805 Series Owner's Manual And Installation Instructions

It is possible for the valve to release a little water through the drain line during each heating period.
This occurs as the water is heated and expands by approximately 1/50 of its volume.
The temperature pressure relief valve must be fitted before the water heater is operated. Before
fitting the relief valve, make sure the probe has not been bent. Seal the thread with Teflon tape -
never hemp. Make sure the tape does not hang over the end of the thread.
Screw the valve into the correct opening leaving the valve drain pointing downwards. Do not use a
wrench on the valve body - use the spanner flats provided. A copper drain line must be fitted to the
temperature pressure relief valve.

Expansion Control Valve (ECV)

Local regulations may make it mandatory to install an expansion control valve (ECV) in the cold
water line to the water heater. In other areas, an ECV is required if the saturation index is greater
than +0.4. The expansion control valve must always be installed after the non-return valve and be
the last valve installed prior to the water heater. A copper drain line must be fitted to the expansion
control valve.

Relief Valve Drain

DN15 copper drain lines must be fitted to the temperature pressure relief
valve and expansion control valve (if one is installed) to carry the discharge
clear of the water heater. Connect the drain lines to the valves using
disconnection unions. The drain line from the valve to the point of discharge
should be as short as possible, have a continuous fall all the way from the
water heater to the discharge outlet and have no tap, valves or other
restrictions in the pipe work.
A drain line from a relief valve must comply with all relevant standards, local codes and regulatory
authority requirements.
A drain line must be no longer than 9 metres with no more than three bends greater than 45° before
discharging at an outlet or air break. The maximum length of 9 metres for a drain line is reduced by 1
metre for each additional bend required of greater than 45°, up to a maximum of three additional
bends. Where the distance to the point of final discharge exceeds this length, the drain line can
discharge into a tundish.
Subject to local regulatory authority approval, the drain lines from the temperature pressure relief
valve and expansion control valve from an individual water heater may be interconnected.
The outlet of a drain line must be in such a position that flow out of the pipe can be easily seen, but
arranged so discharge will not cause injury, damage or nuisance. The termination point of a drain
line must comply with the local regulations. Drain lines must not discharge into a safe tray.
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