Miss match on water pump?

[umpire111]

New boat, have a pump out loo. The water pump installed, 2.9 bar was not of sufficient power to work loo properly so put on a 4.2. Today on 5th day out this somehow caused the Prv on calorifier to blow and fill bilge with water. No hot water at end of sailing. The water pump also does not run smoothly when taps, shower turned on, as though it’s labouring. Any advice please?

[dor]

What sort of pump?   A 2.9 is usually adequate for a narrowboat.  Is the input filter blocked?

 

The 2.9 relates to the flow rate.  Was the 4.2 a higher pressure?  PRVs are normally 3 bar on a boat.  Most pumps will cut out around 2 bar.

Edited July 27, 2020 by dor

[ditchcrawler]

6 minutes ago, umpire111 said:

New boat, have a pump out loo. The water pump installed, 2.9 bar was not of sufficient power to work loo properly so put on a 4.2. Today on 5th day out this somehow caused the Prv on calorifier to blow and fill bilge with water. No hot water at end of sailing. The water pump also does not run smoothly when taps, shower turned on, as though it’s labouring. Any advice please?

Boat toilets dont flush like house toilets, you dont get a great gush. Your new pump is probably over pressurising your system and the water flow unsmooth because the accumulator water pressure was to high for the pre charge pressure. Go back to the lower pressure pump, the PRV may or maynot reeseat and not leak

[umpire111]

5 minutes ago, dor said:

What sort of pump?   A 2.9 is usually adequate for a narrowboat.  Is the input filter blocked?

 

The 2.9 relates to the flow rate.  Was the 4.2 a higher pressure?  PRVs are normally 3 bar on a boat.  Most pumps will cut out around 2 bar.

Tx, it’s a Vetus WP 1220, 4.2 pressure, the 2.9 was fine but didn’t send the water fully around the loo. I’m assuming the higher pressure has caused the prv  to operate and lose all the hot water

[ditchcrawler]

1 minute ago, umpire111 said:

Tx, it’s a Vetus WP 1220, 4.2 pressure, the 2.9 was fine but didn’t send the water fully around the loo. I’m assuming the higher pressure has caused the prv  to operate and lose all the hot water

Thats right, you have over pressurised the system

[umpire111]

Just now, ditchcrawler said:

Thats right, you have over pressurised the system

Think I’ve got it, back to 2.9 ?

[WotEver]

17 minutes ago, umpire111 said:

Think I’ve got it, back to 2.9 ?

Yes

[TheBiscuits]

25 minutes ago, umpire111 said:

Think I’ve got it, back to 2.9 ?

 

Be grateful your calorifier didn't burst before the PRV dumped the pressure! 

 

You saved yourself hundreds of pounds by having a working PRV ...

[Jen-in-Wellies]

Pressure is not the same thing as flow rate, which is what you were trying to improve. The pump cut off pressure is the pressure it will try and take the system to, with all taps closed, before shutting off. In your case, going to a higher shut off pressure pump only succeeded in opening up the PRV on the calorifier. The PRV was doing its job in preventing the cauliflower being over pressurised and possibly failing. Flow rate is the maximum litres per minute, or gallons per hour, or cubic furlongs per fortnight that the pump can push through. The stated flow rate on the pump is with the water being pumped open, straight in to a bucket, so not much applicable in a boat. On the boat, the plumbing pipe size, length, number of elbows, junctions and valves will all decrease the actual flow rate. For example, on my boat with 15mm pipes, the 11l/min pump will only actually push out around 4l/min through the taps.

If this is your first pump out bog, as has been said, don't expect the flush to be like a house one. For one thing, you'll just fill the tank up with flush water and need another pump out. ?

Jen

Edited July 28, 2020 by Jen-in-Wellies

[Tracy D'arth]

Putting a higher pressure pump in is like putting a bigger fuse in an electric circuit because the original blew, asking for trouble and big expense.

TD'

[system 4-50]

I presume you've checked the toilet for limescale etc preventing the inflow coming in smoothly?  Mine flows in all around at a very low flow which is what I understand it should do.  (Jabsco mascerator).

[PeterF]

It might not be applicable in your case, but my thetford cassette loo had an optional restrictor on the water inlet that reduced the flushing flow, removed it and things improved.

[umpire111]

Tx for all responses. Put the 2.9 on  today and so far so good. Anyone want to buy a Vetus WP 1220 pump, a week old?

[Tony Brooks]

59 minutes ago, umpire111 said:

Tx for all responses. Put the 2.9 on  today and so far so good. Anyone want to buy a Vetus WP 1220 pump, a week old?

Keep it, plumb an external pressure switch onto the outlet and you have a spare that allows you to adjust the pressure without invalidating any warrantee. if you get a Square D switch you can also adjust the cut in pressure.

[ditchcrawler]

16 minutes ago, Tony Brooks said:

Keep it, plumb an external pressure switch onto the outlet and you have a spare that allows you to adjust the pressure without invalidating any warrantee. if you get a Square D switch you can also adjust the cut in pressure.

That is what I have done to run the pump well below its rated pressure, hopefully the seals may last a bit longer if not stressed 

[Tony Brooks]

For years I ran JennyB's at between 10 and 15 psi for similar reasons together with a lack of confidence in the plumbing system the boat was built with.

[umpire111]

13 hours ago, Tony Brooks said:

Keep it, plumb an external pressure switch onto the outlet and you have a spare that allows you to adjust the pressure without invalidating any warrantee. if you get a Square D switch you can also adjust the cut in pressure.

There is a pressure control screw on it but couldn’t turn it down enough. The pump was labouring trying to pump at low rate/pressure. 

[Tracy D'arth]

5 minutes ago, umpire111 said:

There is a pressure control screw on it but couldn’t turn it down enough. The pump was labouring trying to pump at low rate/pressure. 

Could you possibly be turning it the wrong way?

[umpire111]

1 minute ago, Tracy D'arth said:

Could you possibly be turning it the wrong way?

Checked Tx, changed pump now

[Tracy D'arth]

11 minutes ago, umpire111 said:

Checked Tx, changed pump now

I did see that.

[Dr Bob]

Who is the boat builder? It is likely if they know what they were doing that the design of the toilet system is ok. Yes these toilets are not as 'good' as house ones and when you flush you may not get water all around the bowl. That is a fact of life on a boat. If you try and bodge the system to get more water around the bowl then instead of 1 or 2 litres  going in per flush, you will double this and therefore reduce the time to fill the holding tank by a half therefore have to pump out more often. How big is your holding tank? We have just taken posession of a brand new boat and there is more water being used flushing than our old boat -yet the bowl isnt fully flushed on the eco setting. We are likely to have to pump out more than on the last boat, every 3 weeks rather than 4 but there are dire warning from the builder that we will void the warranty on the toilet system if we start messing with the water flow. Maybe in a years time!

 

[Tony Brooks]

1 hour ago, Tracy D'arth said:

Could you possibly be turning it the wrong way?

I think so, whatever the OP says. Pumps only labour as engineers understand the term when delivering high pressure and even then its the motor, not the pump that labours. If he was turning the screw the right way to lower the pressure I suspect he may be misdiagnosing cycling as labouring and more cycling is to be executed with a higher output (volume) pump.

 

I can't accept that a screw that reduces the cut out pressure can in any way cause the pump to "labour", if fact it would be the opposite and if you measured the current at cut out you would find it would be less so that proves the pup is finding it  easier to work at lower pressures.

[ditchcrawler]

6 hours ago, umpire111 said:

There is a pressure control screw on it but couldn’t turn it down enough. The pump was labouring trying to pump at low rate/pressure. 

That is probably because it was out of the range of the pump, that is why I fitted the external switch