Fiamma Isensor Aqua 8 Water Pump - keeps dumping out the pressure relief valve (1 Viewer)

[Checkingout]

Hi all, looking for some guidance from you skilled and intelligent funsters.

We have a 7 l/min Fiamma isensor aqua 8 water pump with a Truma Combi 4 E water heater system and a frost protection type pressure relief valve.

Our problem usually happens after we have switched on the water heating and the water has heated up fully whereby randomly the pressure relief valve opens and dumps water out the drain valve, the pump runs for a couple of seconds and stops, then the prv opens and dumps again, the pump starts........ this just keeps pulsing like this wasting our water. Sometimes this stops by itself after a few cycles, sometimes we can stop it by rapidly opening and closing a tap, sometimes we have to turn the pump off at the controller. Frequently when we use a tap, the pressure dumping/pump running cycle starts up but often it just does it by itself.

I understand that when you heat up water in a closed circuit, the pressure will rise and the prv should quite rightly open to relieve that pressure, however, something here is out of balance. Either the pump is delivering pressure above the prv setting (I don't think this can be adjusted on the isensor Aqua 8) or the prv is set too low or is not closing off fast enough after relieving pressure leading to the pump having to start up? I don't know why it should be so much worse once the water has heated up? We had a slightly different problem a few months ago and had a new prv installed. It has been fine until the last week or when this problem started and is getting worse.

It should still be covered by warranty but we are in Greece right now and about to head to Turkey and I'm not sure I can find someone to repair this.

Any cunning plans for me to try or have others had this experience.

Thanks

 

[Lenny HB]

I assume you are talking about the valve in the T piece at the top of the boiler, quite common for them to fail but not normally in a new van. A tempory fix is to clamp the drain pipe, the valve is only there to let air out of the tank when it is filled from empty. Another thing you can try is thak the valve off and soak in a solution of hot white wine vinegar as it could be a build up of calcium in the valve.

 

[Checkingout]

Hi Lenny, no it's this one, which is a separate valve piped into the circuit.

i
We are in Greece, daytime around 25C, night time around 13C so it is not dumping to protect from frost. It is supposed to be a step up from the basic pressure relief valve. Thanks and get back to work.

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[Lenny HB]

Not heard of them going faulty before, you can jam the button in at the bottom with a piece of timber or something wedged against it.

 

[Happy1]

Got the same problem, mine only dumps once maybe twice when water gets hot, not tried experimenting yet with eco Vs hot water settings so see if temp is the issue?

 

[Happy1]

Forgot to say the cp panel showed an overpressure fault so had an accumulator fitted hoping that would do the trick but it only stopped pump pulsing when tap open a fraction.
Faulty batch of frost control valve?

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[Checkingout]

No way of securing this frost control valve in the closed position. The pump produces 1.5 bar, the frost/pressure control valve is supposed to open at 2.8 bar. The boiler relieves pressure out a different pressure relief with a separate drain. Only logical answer is that the frost control valve is faulty and is actually opening at a much lower pressure. I have blocked the drain from the frost valve for now and will get a replacement frost control valve when I can get one under warranty and in the meantime keep south for the winter to avoid frosty conditions.

 

[The Nomad]

We had similar problem with the frost control dump valve in our previous MH. Kept sporadically dumping when domestic water was hot.
A MH dealer techy said yeah its a rubbish design and loads of them do that as they are too sensitive, and just wedged its switch in the closed position. Ran the mh for about 4 years after that, used it a LOT through that period and never ever had any problems thereafter.

 

[The Nomad]

No way of securing this frost control valve in the closed position. The pump produces 1.5 bar, the frost/pressure control valve is supposed to open at 2.8 bar. The boiler relieves pressure out a different pressure relief with a separate drain. Only logical answer is that the frost control valve is faulty and is actually opening at a much lower pressure. I have blocked the drain from the frost valve for now and will get a replacement frost control valve when I can get one under warranty and in the meantime keep south for the winter to avoid frosty conditions.

Is it not the type with a switch to marginally drain down but also a blue Pop up valve button? On ours it was the button that kept popping out, so that's what we gently held in with a very thin piece of cane wedged in place across it.

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[Lenny HB]

Well I've heard about them now, I've had them in the last 2 vans without any problems, fingers crossed.

Are they by any chance more prone to failing on pressurised stems as these tend to run at higher pressures than submersible pumps and in the OP's post could the pressure from the pump too high.

 

[Checkingout]

On our Truma valve, the button needs to be pressed in otherwise it is just open to the drain and no way to block shut. There should be 1.3 bar difference between what the pump can produce and when the valve opens to dump pressure so it should be OK (provided the valve isn't faulty and opening at a much lower pressure. There are some videos on this link of the valve, then the pump, then the drain valve dumping my water after the tap was turned off. Turn on the sound so you can hear the cycling. Taping up the outlet pipe hasn't worked as the pump generates too much pressure. Will just have to manage it until I can find a repair agent to fix under warranty (the valves are 139 Euro)

https://www.dropbox.com/sh/5u8ykpi1527gqxz/AADhDaEB-SPnB0eq7aaEvVL6a?dl=0

 

[Shrimp]

We put a peg on our frost valve pipe but you have to remember it's there!

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[Lenny HB]

We put a peg on our frost valve pipe but you have to remember it's there!

Different type of valve you can't do that on the newer ones.

 

[jockaneezer]

It's difficult to guess the size of the pipework going through the frost protection valve from the photos, but an option might be to buy the correct sized straight pushlok connector and undo the pipes either side of the dump valve by pushing the little pipe collars in and pulling the pipes out, then rejoining them with the straight connector as a temporary measure to bypass the valve. Screwfix and plumbers merchants would be the sort of places that stock them.

 

[The Nomad]

On our Truma valve, the button needs to be pressed in otherwise it is just open to the drain and no way to block shut. There should be 1.3 bar difference between what the pump can produce and when the valve opens to dump pressure so it should be OK (provided the valve isn't faulty and opening at a much lower pressure. There are some videos on this link of the valve, then the pump, then the drain valve dumping my water after the tap was turned off. Turn on the sound so you can hear the cycling. Taping up the outlet pipe hasn't worked as the pump generates too much pressure. Will just have to manage it until I can find a repair agent to fix under warranty (the valves are 139 Euro)

https://www.dropbox.com/sh/5u8ykpi1527gqxz/AADhDaEB-SPnB0eq7aaEvVL6a?dl=0

That is the same valve type as ours was that I referred to in my dealer post.
Just put something off the similar diameter on top of the blue pop out valve ( eh a plastic bottle top) and then wrap insulation tape round it and the body of the valve to keep pressure on it so it keeps the button held in.

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