Air Con raw water pump not pumping

[marcochi76]

Hello,
the white pump in the attached photos is the raw water pump for the air conditioning system.
Unfortunately, we activated the aircon while the water stop cock was closed. It run for few minutes. When I realised it, the pump was already hot.
Since then, I have the impression the pump is not pumping any water.
On the body of the pump it is suggested to fill the body of the pump with water after long period of non usage.
Maybe when I run the pump with the stop cock closed, the pump suck air, emptied and now we have to re-engage it?
Or maybe I damaged the prop when running it with stop cock closed?

I tried to remove one of the 2 white hoses, but it is super hard to remove them.
What would you suggest me to do?
Thanks!

 

[markc]

I would doubt that the impeller is damaged. I have a Calpeda pump on my AC and if the boat has been out of the water it can need re-priming and there is a nut that you can use to purge the air / use to fill water. If not, as you say, you need to remove one of the pipes (inlet, not outlet) and fill with water. If the pipe is hard to remove, try a little heat (hot water or hair dryer) and rotate the pipe rather than pull it to break the seal.

 

[Mr Googler]

Have you got a strainer before the pump?

I did the same thing. Close the Seacock, fill the strainer until it won’t take anymore, put the lid back on the strainer (to keep the water in the system), open Seacock and give it a go

 

[marcochi76]

the pump is below the sea level, so when the seacock is open, water should flow by pressure and fill the pump? isn't it right?

 

[marcochi76]

this is the seacock with strainer on top of it.
it is in the bilge, below the pump.

 

[marcochi76]

From the manufacturer:

The liquid ring self-priming electro-pump "CP" series, with star impeller, have an outstanding self-priming capacity (up to 8m vertical). Only at the first start or after a long term disuse, it is necessary to fill the pump’s body with water, then, the pump automatically primes, also with the suction pipe empty. We suggest to install a filter and a clapet valve on the suction pipe in order to avoid a water reflux.

 

[markc]

You can put a non-return valve in the inlet hose if the water regularly drains back, but I would just try and get it going now. I would certainly pull off the inlet hose at the pump and fill with water - if your pump is below sea level then I'd turn off the seacock first. I'm not sure if it's possible to get an airlock in the pipework running it dry, but filling up the pipes will deal with it if you have. It's certainly worth doing this before getting drastic

Another thought - I'm assuming that you don't have a valve at the discharge end that's been shut off?

 

[marcochi76]

Another thought - I'm assuming that you don't have a valve at the discharge end that's been shut off?

The exit valves are open, I checked.

 

[Mr Googler]

The big loop of pipe takes the circuit above sea level I would guess. Could be air trapped there but if it can pull 8m head?

Maybe stick a freshwater hose pipe up the intake hose via the strainer to give it a shove and prime it.

 

[Portofino]

You pic shows a face plate and bulky pump body .I would remove that and take a peek .Thinking what ever the impeller is made of has failed now to draw “ 8M “:It’s below the WL or near so should self prime when the cock is open .
Turn the inlet cock off btw before opening it up .
You have checked the strainer screen ? It’s not been mentioned.

Here is a pic of my Calpidi .Note the circular pump body .Theses are brass / bronze ( or what ever metal ) impeller and survive running dry FWIW .
Note the bleed bolt on top of said impeller body .
Below it is the inlet valve / strainer with Perspex lid and handle nearby .


You can see the sea through the strainer - green

Edit I think your pipes all wrong too .It’s toilet soil pipe used for bowl to H tank .It could ballon under a certain pressure and split between the wire ribs Close that cock when you leave the boat .

Inlet and high P water should be fibre as well as wire ribbed .reinforced like the pic above .

Like I say 1- ask for text drive before buying a boat .Not the issue here .
2- equally important blag a visit into the ER for a peek .Tells a lot .

 

[Mr Googler]

You pic shows a face plate and bulky pump body .I would remove that and take a peek .Thinking what ever the impeller is made of has failed now to draw “ 8M “:It’s below the WL or near so should self prime when the cock is open .
Turn the inlet cock off btw before opening it up .
You have checked the strainer screen ? It’s not been mentioned.

Here is a pic of my Calpidi .Note the circular pump body .Theses are brass impeller and survive running dry FWIW .
Note the bleed bolt on top of said impeller body .
Below it is the inlet valve / strainer with Perspex lid and handle nearby .

View attachment 125204
You can see the sea through the strainer - green

Edit I think your pipes all wrong too .It’s toilet soil pipe used for bowl to H tank .It could ballon under a certain pressure and split between the wire ribs Close that cock when you leave the boat .

Inlet and high P water should be fibre as well as wire ribbed .reinforced like the pic above .

Like I say 1- ask for text drive before buying a boat .Not the issue here .
2- equally important blag a visit into the ER for a peek .Tells a lot .

his is bronze impeller…..says so in the screenshot of the spec he attached

 

[Portofino]

his is bronze impeller…..says so in the screenshot of the spec he attached

Can you show me where ps ?
Says “casing” like a VP pump or any Jabsco pump , but they have rubber impeller s
Looks silent from a impeller pov to me .
Any how I never said it wasn’t said “ what ever type “ Cos currently what ever is in there has a face plate and is not working .

 

[Mr Googler]

Can you show me where ps ?
Says “casing” like a VP pump or any Jabsco pump , but they have rubber impeller s
Looks silent from a impeller pov to me .
Any how I never said it wasn’t said “ what ever type “ Cos currently what ever is in there has a face plate and is not working .

 

[marcochi76]

Thanks all for your messages.
Given the bronze impeller, it seems difficult that I damaged the pump by running it 5min with the seacocks closed.
So it appears as a priming / air issue.
I will really like to avoid removing the inlet hose, as I fear to damage it.
I will follow the suggestion of inserting a freshwater hose pipe through the strainer up to the pump to fill it with water, and check if that helps.

Also it appears strange to me that I do not have any bleed bolt anywhere on the pump.

 

[DAKA]

Thanks all for your messages.
Given the bronze impeller, it seems difficult that I damaged the pump by running it 5min with the seacocks closed.
So it appears as a priming / air issue.
I will really like to avoid removing the inlet hose, as I fear to damage it.
I will follow the suggestion of inserting a freshwater hose pipe through the strainer up to the pump to fill it with water, and check if that helps.

Also it appears strange to me that I do not have any bleed bolt anywhere on the pump.

happens All the time with ours.
our outlets are above the waterline
just use the marina fresh water hose in the outlet

few bubbles will emerge from under the hull and it’s good to go.
we have 3 units and the guest cabin hardly gets used so that needs 1/2 hour of reverse hose treatment Every other year.

 

[marcochi76]

just use the marina fresh water hose in the outlet
few bubbles will emerge from under the hull and it’s good to go.

I run the air con again this morning and the pump finally went working again.
and a lot of air went out of the outlets (under water line).
maybe because of the colder temperature, the volume of air reduced and that helped self-priming?

DAKA: good to know your exeperience!

 

[Mr Googler]

I run the air con again this morning and the pump finally went working again.
and a lot of air went out of the outlets (under water line).
maybe because of the colder temperature, the volume of air reduced and that helped self-priming?

DAKA: good to know your exeperience!

Just a bit of good luck I would say ? We all need that from time to time ?

 

[Kub Cat]

My view on this.

The pump inlet is on top of the impeller, so self priming is difficult. The hose going from the seacock to the strainer to the pump cannot go down if it is to self prime. It must be level, or preferably slightly upwards.

Self priming pumps often have the inlets in the middle or side entry for this reason.

The water from the sea strainer doesn’t ‘fall’ into the pump instead you have air in the upper loop of the pipe. It is an upside down U and the air rises to the top.

Maybe some water drained back down into the pump from the air con, or whatever, but the air bubble filled with water and it primed.

Great it is working and now the air is out, you shouldn’t have any more problems.

 

[marcochi76]

Thanks kubcat