Volt fail relay

[Rheilly Phoull]

G'Day All
Anyone know what the rationale behind the "volt fail" relays found in hot
water heaters (mainly instantaneous) was??
Here I am talking about a manually reset relay that needed to be reset
whenever the power went off for a second or more.
--
Regards ........... Rheilly Phoull

 

[KLR]

On Wed, 9 Jun 2004 19:43:00 +0800, "Rheilly Phoull"
<Rheilly@bigpong.com> wrote:

G'Day All
Anyone know what the rationale behind the "volt fail" relays found in hot
water heaters (mainly instantaneous) was??
Here I am talking about a manually reset relay that needed to be reset
whenever the power went off for a second or more.

Im not aware of such a feature in the typical domestic hot water
system (ie - large capacity, thermostat controlled and not instant
heat)



In instant heat situations I would imagine the following scenarios are
possible for this feature:

Probably to prevent the situation where the water would go cold - and
the user mightn't realise the power has gone off - and would react by
turning the hot tap higher to increase the heat. The power returns
unexpectedly and before you know it someone gets badly burnt.

Particularly nasty if its a shower !



Another possibility is if the power goes off - the person realises
this - and stops using the hot water - goes away and does something
else and doesnt remember to turn off the water heater and the power
comes back on and the thing sits boiling away all day, or cycles on
and off with the thermostat or safety cutout, drawing large amounts of
power in the process.

 

[Rod Speed]

<KLR> wrote in message news:c3ffc0d7f8mhf10l0o7r14ook76j7ijshe@4ax.com...

On Wed, 9 Jun 2004 19:43:00 +0800, "Rheilly Phoull"
Rheilly@bigpong.com> wrote:


G'Day All
Anyone know what the rationale behind the "volt fail" relays found in hot
water heaters (mainly instantaneous) was??
Here I am talking about a manually reset relay that needed to be reset
whenever the power went off for a second or more.


Im not aware of such a feature in the typical domestic hot water
system (ie - large capacity, thermostat controlled and not instant
heat)



In instant heat situations I would imagine the following scenarios are
possible for this feature:

Probably to prevent the situation where the water would go cold - and
the user mightn't realise the power has gone off - and would react by
turning the hot tap higher to increase the heat. The power returns
unexpectedly and before you know it someone gets badly burnt.

Particularly nasty if its a shower !



Another possibility is if the power goes off - the person realises
this - and stops using the hot water - goes away and does something
else and doesnt remember to turn off the water heater and the power
comes back on and the thing sits boiling away all day, or cycles on
and off with the thermostat or safety cutout, drawing large amounts of
power in the process.

Instant heaters dont have to be turned on
to get hot water, so this last one cant fly.

 

[Bernard Morey]

"Rod Speed" <rod_speed@yahoo.com> wrote in message
news:2iqc2tFpmdjvU1@uni-berlin.de...

power in the process.

Instant heaters dont have to be turned on
to get hot water, so this last one cant fly.

Of course they have to be turned on to get hot water. No water flow
detected - gas can't light.

 

[Phil Allison]

"Bernard Morey" <

"Rod Speed" <..

Instant heaters dont have to be turned on
to get hot water, so this last one cant fly.


Of course they have to be turned on to get hot water. No water flow
detected - gas can't light.

** The "gas can't light " ??????

Oh dear.



............... Phil

 

[The Real Andy]

On Thu, 10 Jun 2004 17:32:21 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

"Bernard Morey"
"Rod Speed" <..

Instant heaters dont have to be turned on
to get hot water, so this last one cant fly.


Of course they have to be turned on to get hot water. No water flow
detected - gas can't light.


** The "gas can't light " ??????

Oh dear.

No power, gas cant light, gas accumulates, power comes back on...BOOM.

 

[Rheilly Phoull]

"The Real Andy" <.pearson@wayit_dot_com_dot_au_remove_the_obvious_to_reply>
wrote in message news14gc0diinlkljcs840bn5klbd6r46nljl@4ax.com...

On Thu, 10 Jun 2004 17:32:21 +1000, "Phil Allison"
philallison@tpg.com.au> wrote:


"Bernard Morey"
"Rod Speed" <..

Instant heaters dont have to be turned on
to get hot water, so this last one cant fly.


Of course they have to be turned on to get hot water. No water flow
detected - gas can't light.


** The "gas can't light " ??????

Oh dear.

No power, gas cant light, gas accumulates, power comes back on...BOOM.

Yeah yeah !! OK enough with the gas already.
What it is about, is that I have a 3~ 50 litre storage heater equiped with
such. It goes well and can recover the temperature of the water quickly
from cold. Since it has thermal cutouts and thermostatic control I'm
thinking that the "no volt" protection is really not needed since the normal
condition for this unit is "On". I have to do a bit of work on it and I
reckon I'll lose that feature. Anyone see a problem there ??

--
Regards ........... Rheilly Phoull

 

[Rod Speed]

Bernard Morey <bernardmorey@optusnet.com.au> wrote in message
news:40c80699$0$1583$afc38c87@news.optusnet.com.au...

Rod Speed <rod_speed@yahoo.com> wrote
KLR> wrote

Another possibility is if the power goes off - the person realises
this - and stops using the hot water - goes away and does
something else and doesnt remember to turn off the water
heater and the power comes back on and the thing sits
boiling away all day, or cycles on and off with the thermostat
or safety cutout, drawing large amounts of power in the process.

Instant heaters dont have to be turned on
to get hot water, so this last one cant fly.

Of course they have to be turned on to get hot water.

I obviously meant that you dont have to turn them
on just before you want hot water, you can leave
them turned on all the time and they will heat the
water auto when the hot water tap is used.

No water flow detected - gas can't light.

He clearly wasnt talking about a gas instant hot water system either.

 

[Rod Speed]

Rheilly Phoull <Rheilly@bigpong.com> wrote in
message news:2iqpsrFplvi9U1@uni-berlin.de...

What it is about, is that I have a 3~ 50 litre storage heater equiped with
such. It goes well and can recover the temperature of the water quickly
from cold. Since it has thermal cutouts and thermostatic control I'm
thinking that the "no volt" protection is really not needed since the normal
condition for this unit is "On". I have to do a bit of work on it and I
reckon I'll lose that feature. Anyone see a problem there ??

Its a bit of a worry that it has that in the first place.

Maybe its meant to be an instant heater, not storage,
and is being used as a storage heater now or something.

 

[Yobbeaux]

"Rheilly Phoull" <Rheilly@bigpong.com> wrote in message
news:2iqpsrFplvi9U1@uni-berlin.de...

"The Real Andy"
.pearson@wayit_dot_com_dot_au_remove_the_obvious_to_reply
wrote in message news14gc0diinlkljcs840bn5klbd6r46nljl@4ax.com...
On Thu, 10 Jun 2004 17:32:21 +1000, "Phil Allison"
philallison@tpg.com.au> wrote:


"Bernard Morey"
"Rod Speed" <..

Instant heaters dont have to be turned on
to get hot water, so this last one cant fly.


Of course they have to be turned on to get hot water. No water flow
detected - gas can't light.


** The "gas can't light " ??????

Oh dear.

No power, gas cant light, gas accumulates, power comes back on...BOOM.

Yeah yeah !! OK enough with the gas already.
What it is about, is that I have a 3~ 50 litre storage heater equiped with
such. It goes well and can recover the temperature of the water quickly
from cold. Since it has thermal cutouts and thermostatic control I'm
thinking that the "no volt" protection is really not needed since the
normal
condition for this unit is "On". I have to do a bit of work on it and I
reckon I'll lose that feature. Anyone see a problem there ??

--
Regards ........... Rheilly Phoull


Another posibility might be that it was in use with an electric water pump

to supply water pressure.
when the poower is lost the heater is shut off because off possible no water
in tank situation when the power returns

if you have a good town supply water i don't see any harm in removing it

In the mines we used no volt relays so as someone had to go around and look
at the machinery as it powered back up

must have been some reason for it

cheers
john