Water pump pulsing

[Andrew Dwyer]

If the pulsing bothers you when showering (eg. if the resultant temperature varies too much) simply open a tap slightly, and the combined flow should allow the pump to run continuously.... but of course you will waste some water...

It doesn’t bother me really other than the fact that I don’t think it was happening before I drained it and lifted it together with the tank and wonder what has changed ?
I don’t see it being detrimental to the pump as since I’ve noticed it I’ve realised that the neighbours do the same.

Only on cold water !!, shower heaters are next on the list, after painting the house, rerouting the drain pipe from car port roof, fit sunshades to the sala, etc etc

[David B in Thailand]

Depending on where you buy a Hitachi Water pump, you can get excellent intelligent after the sales service from both Hitachi distributors in Thailand. I recently spoke with a Toyobo Hitachi technical representative in English in Buriram regarding Hitachi water pumps.   http://www.toyobothailand.com/?lang=en&id=

[Andrew Dwyer]

Well !!

My pump is back to how it was before ( cycling only when a tap is partially opened) !!
Without any interference from me in the last few days.

My only thoughts are that it must have been a change in voltage ( as stated by someone earlier) or air has finally got out of the system, I tend to think it is the former as I opened all taps/showers etc and ran for a while.

Anyway, thoughts anyone ?

[Mike45]

I was turning on an additional tap when showering. The constant cycling is bad for the pump and it will fail prematurely.

I just fixed it by installing a 24 litre pressurized tank.

[shaemus]

On 4/15/2019 at 6:22 PM, Andrew Dwyer said:

Well !!

My pump is back to how it was before ( cycling only when a tap is partially opened) !!
Without any interference from me in the last few days.

My only thoughts are that it must have been a change in voltage ( as stated by someone earlier) or air has finally got out of the system, I tend to think it is the former as I opened all taps/showers etc and ran for a while.

Anyway, thoughts anyone ?

i noted from another thread that you fixed the problem. how did you do this?

 

[CGW]

On 4/15/2019 at 5:22 PM, Andrew Dwyer said:

Anyway, thoughts anyone ?

My thoughts on "intermittent faults" are they generally come back and bite you in the bottom at the most inconvenient time 

[Andrew Dwyer]

i noted from another thread that you fixed the problem. how did you do this?
 

Actually I didn’t do anything, went away for a couple of days over Songkran and when I came back noticed that it was back to how it was before ( pump running constantly when toilet flushes or tap/shower opened ). This was 14 days after the “ problem “ appeared !!

I did notice that the pump was a lot louder during the two weeks it was cycling ( or maybe just appeared so ? ) but now is quiet as before.

I put this down to air in the system ?

Steve 73 suggested it was dirt ( sludge ) trapped in the pump and could well have been although I did clean out the tank while it was down and on cleaning the shower heads found nothing but the usual limescale buildup on the nozzles.

[Andrew Dwyer]

My thoughts on "intermittent faults" are they generally come back and bite you in the bottom at the most inconvenient time 

I’m thinking lightening doesn’t strike twice in the same place [emoji51]

[CGW]

2 minutes ago, Andrew Dwyer said:

I’m thinking lightening doesn’t strike twice in the same place

Thinking or hoping? 

[Andrew Dwyer]

Thinking or hoping? 

Let’s just say, I’m not in the slightest bit religious but prayers have been said !! [emoji51]

[CGW]

5 minutes ago, Andrew Dwyer said:

Let’s just say, I’m not in the slightest bit religious but prayers have been said !!

It doesn't hurt to cover all the bases! ...........

[shaemus]

1 hour ago, Andrew Dwyer said:

Actually I didn’t do anything, went away for a couple of days over Songkran and when I came back noticed that it was back to how it was before ( pump running constantly when toilet flushes or tap/shower opened ). This was 14 days after the “ problem “ appeared !!

I did notice that the pump was a lot louder during the two weeks it was cycling ( or maybe just appeared so ? ) but now is quiet as before.

I put this down to air in the system ?

Steve 73 suggested it was dirt ( sludge ) trapped in the pump and could well have been although I did clean out the tank while it was down and on cleaning the shower heads found nothing but the usual limescale buildup on the nozzles.

did you look a the check valve? its under the plastic cap with 3 screws.

 

[Andrew Dwyer]

did you look a the check valve? its under the plastic cap with 3 screws.
 

I must admit I didn’t.

[Singtoo]

I think i missed the answer which is most likely the problem to the fast on/of switching of the pump.

The air-bubble in the pressure tank is gone.

So there is only water in the pressure tank underneath the the pump.

So there is need to empty the pressure tank by unscrewing the plastic covers like in the part print screen.

There are 2 of these.

 

 

Step 1 - take out plug or breaker from the pump.

Step 2 - close in and out valves.

Step 3 - slowly unscrew the low side plug. Be carefully as the tank is still under pressure!!! let the pressure slowly escape from the pressure tank.

Step 4 - unscrew the bottom and top screw totally and wait until water is out of the tank.

Step 5 - When tank is empty of water. Do these step in reverse.

Step 6 - Wait or pump refills itself and stop on high pressure.

Step 7 - Test nearby water tap to see/hear or pump runs with longer runs between minimum and maximum pressure.

[emptypockets]

On 4/9/2019 at 6:53 PM, steve73 said:

Pumps produce both pressure and flow... the higher the flow rate, the lower the discharge pressure, but as the flow is choked back by throttling the outlet somewhere, the pressure increases, until there is no flow and the pump is what's called "dead-headed".   This pressure vs. flow relationship is called the pump curve.

 

The pressure switch is designed to shut off the pump when it operates at a low flow to prevent it dead-heading since it will continue to run but with no flow to cool it, it will rapidly overheat and damage itself.  

 

The difference in pressure between low flow and no flow (say 5-10% or rated capacity) is usually very flat, so the setting of the pressure switch to shut off the pump is very critical.  Set it too low and the pump will cycle, set it too high and the pump will never switch off (and damage itself).  But you can usually improve the factory settings, and allow cycle free operation at lower flowrates than "as supplied".... but you do risk damaging the pump.

 

One problem especially here in T/L is that the supply voltage can vary a lot.. higher voltage make the pump run faster (and so generate a higher pressure, which makes it more prone to cycling), or if the voltage drops a little. the pump will run slower and can never generate enough pressure to shut itself off - i.e. overheat and damage. 

 

If you do suffer with low voltage, you can adjust the switch setting to make it shut off at a little lower pressure, (but it will tend to cycle more when the voltage is normal). 

 

If excessive cycling does bother you, and you can't increase the set pressure due to occasional periods of low voltage, you can install a flow switch on the pump outlet.  This will then shut off the pump when it detects no flow regardless of the pressure, and will switch the pump on when it detect a falling pressure (such as when you open a tap).. But they are expensive (c. 2-2,500 bt) and can easily be damaged with voltage surges (I got through 3 of them in a year before I replaced them with a simple pressure switch.)  

Get one if these. Combined pressure and flow switch pump controller. Global house. Starts the pump on low pressure and keeps the pump on until the flow stops.

[steve73]

21 hours ago, emptypockets said:

Get one if these. Combined pressure and flow switch pump controller. Global house. Starts the pump on low pressure and keeps the pump on until the flow stops.

I agree, these are perfect when low voltage prevents the basic pressure switch from shutting the pump off on a dead-head, but they are sensitive to voltage surges, and they're relatively expensive to replace when they keep failing.... ref. my previous post.