- This topic has 12 replies, 5 voices, and was last updated 20 years, 9 months ago by
tobes.
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Andrew Walter
i installed an infinity 20 LPG hws
the problem i am having is that when the hot and cold water are both turned on the water pulses and goes from the desired temp to hot and back again, it doesnt seem to pulse when just the hot or cold are turned on or in any other fixture(basin, sink)
the connections to and from the unit are all in 20mm cu the shower is the closest fixture to the unit,
i have not installed many of these units and have not had a problem like this b4 any advice would be apreciated.
cheers
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Tobes. Is the cold inlet pressure to the Hws equal to cold at the outlets?
Bob -
i would imagine so, except that the shower cold inlet is teed off from 20mm to 15mm but only about 250mm, the connection to the heater is 20mm (as recommended and has a 20 mm connection)
why? do you think this could be the problem? -
You used a ball valve on the cold inlet ???
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Tobes, have you got a watersaving shower head?
Bob -
It does not have a water saving showerhead, and the cold water valve is a 20mm rmc duo valve (i know you dont have to use them for instantanious they just look neater) could this be the problem? as i said it is only happening in the shower and only when both taps are on the water goes hotter but never colder
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Tobes, Without inspection, I believe that it could be a pressure differential problem. The infinity is a high temp Hws, Hot water will always increase in temperature.
Are you in Australia?
The laws relating to the installation of HWS in Australia are quite clear, have you installed the mandatory Tempering valve? You should already be aware that Hot Water BURNS.
The implications for you as the installer are fairly onerous should any person get scalded.
Regards Bob -
has rmc TVA50HP
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Tobes. Have you checked the tempering valve accuracy?. It shouldnt have more than + or -2Deg.
Did you check the outflow temp when full hot water was coming through? is it constant? Have you checked the filters & non return valves on the Tempering valve? Check the incoming pressure to the HWS & h&C to the Tempering Valve, also the warm & cold water pressure at the Shr.
Regards Bob -
Dump the duo valve, use a ball valve as per the instructions. you are restricting the flow over the thermostatic coupling. Sounds like I might know summit LOL …. remove the duo valve and fit a ball valve
DISCLAIMERAll advice is given with-out seeing the job, and hence all advice MUST be taken as advice with limited knowledge on the exact situation. NO responsibility can or will be taken. And yes, I am a licensed Plumber and Drainer with my own business in Brisbane Australia
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seems as if you don’t know your AGA601, old feller.
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Spook. This is the Plumbing Post. We have been talking about Plumbing & the changing temperatures, Bungie only mentioned that the use of a Duo valve may interfere with the flow through the Thermostat.
I particularly dont like Duo valves because they aid water hammer.
I feel that Tobes’s problem lays in the Tempering valve – not the heater – it most probably is caused by differential pressures? any suggestions?
I keep thinking that if the Hws is plumbed from the 20mm water service & there is 250mm from the 20mm to the shr. Where is the HWS in relationship to the Shr? Has the water service been sized? Remembering that if there is a Tempering valve installed then say 50% of the water to the shr is warm (which is made of say 50% cold & 50% hot) & the Cold is cold. so depending on the proper functioning of the trempering valve & provided the sizing is right, providing the pressure is equal and the temperature is constant there should be no problem. Be the heating method electrical, gas or solar.
Regards Bob -
ttok off the duo valve as advised, seems to not be pulsing any more, thanks for advice everyone much appreciated
tobes
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