Pump issue

[tkk]

Hi all,
Technical issue. When one tap is on in full hot water position the pump works in “pulses” 5 secs on 3 off. It works normally when two taps are o. Boiler is Alde with Truma drain/frost safety/drain valve, was running ok until recently
Thanks
Tk

 

[pappajohn]

Restriction in pipework or tap.
Does the tap/s have a filter ring on the end?
Unscrew and soak in vinegar to clear any limescale buildup.

 

[HandyAndy]

pump is stopping probably because pressure is building up where it shouldn't be. As papa says, check for kinked pipework and other restrictions. Could be limescale build up in the hotwater tank even (long shot)

 

[tkk]

Thanks, will look at it from this angle

 

[pappajohn]

Could be limescale build up in the hotwater tank even (long shot)

That's possible.
My last caravan had an Alde 3020 system which had a small leak on the heating pipe.
The previous owner had, for a long time, used plain tap water rather than antifreeze because of the leak and cost of antifreeze to top up. .
Once I repaired the leak the boiler would only get to a certain temp then cut out as the boiler itself was overheating due to a restricted flow through the heating pipework.
The inside of the pipe was around 50% limescale.

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[Mr Colpot]

We have a similar issue. Van is 5 years old and the pump pulses but only on cold feed and not when tap on full. Haven't tried it with more than 1 tap on though. Took spray nozzle off kitchen tap as it was spraying everywhere but in the sink, cleaned it an now it wont stick back in the tap. Suggestions to cure the pulsing range from adjusting the pressure switch (difficult to get to without taking the pump out), replacing the pump, fitting some kind pressure chamber.....

 

[tacr2man]

Bodge fix turn on another cold tap or hot tap this will increase flow and stop pressure build up causing cycling , other wise as mentioned look for something causing flow restriction in hot water side of things eg scale .
This could also be fixed by fitting accumulator on exit side of pump , I have always done so in self builds, as it allowed fitting of powerful pump (for when showering) but gets over the pump cycling when needing a slow flow rate from a tap for something else. .

 

[tkk]

Seems a bit early for lime scale (5 months old) no problem with cold flow. Alde handbook mentions “air cushion” needing to be restored by short opening of safety/drain valve, with picture of Alde valve. Mine seems to be a Truma valve. Have tried this manoeuvre without success. Anyone got any thoughts on this as a possible cause?
Ta.
TK

 

[PepnKook]

Got an Alde system in our new van, has always "pulsed", but the water flow is consistent from all taps. I just assumed this was how it worked! Am I wrong? Should the pump be constant? Seems to work fine with no issues with pressure. Have had two taps open at the same time, both hot and cold, but makes no difference.

 

[tonyidle]

Fit an accumulator and / or turn up system pressure.

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[andy63]

Surley there is nothing wrong with the pump pulsing.. it's supposed to do that to cope with a range of flows.. as long as it doesn't pulse too frequently.. something like not less than two seconds intervals...I cant remember but the pump instructions state a time..
They also point out that the screw on these pump heads do not alter the pressure as such... that is governed by the spring fitted in the pump casing... what it does do is alter the distance between the contacts and therefore the time of pulsing but my experience would suggest its only marginal adjustment you get..
Fitting an accumulator can help but again you have to play about with the pressure in it to get an optimum setting...when you are setting the accumulator air pressure open a tap with pump off to release the pressure and pressurized the chamber.. if you check the pressure after the pump has been running and shut down the system pressure will always be the max pump pressure..
Andy..

 

[PepnKook]

Or, even better, actually look at your system and realise that it already has an accumulator fitted as standard and the sound you thought was pulsing was in fact normal operation (wasn't pulsing at all, just my memory of it from two weeks ago thought it was )