Heater water not circulating

[StuartAdair]

Hi folks,

Got a ListerPetter LPW4 fitted in a Norfolk Broads boat. Ran her up river yesterday and the hot water was cold. I've had a check of the system today and its all a bit strange. Referring to the attached diagram I pulled off pipe 1 with the engine running and a tiny trickle of water came out (Flow to the heater). Same for pipe 2 (Return from the heater). The engine isn't over heating, runs fine and when warmed up you can feel heat in the places I've marked as hot.

Any ideas why the water isn't moving around the heater ?

Thanks
Stu

[Tracy D'arth]

Air lock in the calorifier coil. Check how the vent is fitted to the top connection on the calorifier. A picture is best. 

 

With the engine running fast, vent the top hose on the calorifier --- carefully!

[Tony Brooks]

The pipe 1 seems to be fitted onto a swept T with the sweep the wrong way for optimum feed to the calorifier.

 

Where is the other end of that T connected to?

 

What type of engine thermostat do Nanni use? If it is a barrel type bypass thermostat it might be limiting the flow to the calorifier when the engine is hot.

[Tony Brooks]

2 minutes ago, Tracy D'arth said:

Air lock in the calorifier coil. Check how the vent is fitted to the top connection on the calorifier. A picture is best. 

 

With the engine running fast, vent the top hose on the calorifier --- carefully!

 

My first thought but he said: Referring to the attached diagram I pulled off pipe 1 with the engine running and a tiny trickle of water came out (Flow to the heater).  And if it was an airlock in the calorifier it should gush out with a few revs on the engine. I suspect the third invisible pipe on the T may be a thermostat bypass and that might imply a bypass thermostat closes it off when hot.

 

[Tracy D'arth]

6 minutes ago, Tony Brooks said:

The pipe 1 seems to be fitted onto a swept T with the sweep the wrong way for optimum feed to the calorifier.

 

Where is the other end of that T connected to?

 

What type of engine thermostat do Nanni use? If it is a barrel type bypass thermostat it might be limiting the flow to the calorifier when the engine is hot.

That looks like any other Lister LPW plumbing as I remember it. I thought they had a standard single poppet stat in?

[StuartAdair]

Thank you for all of your replies. The hidden pipe at the back goes onto a temperature sensor and doesn't flow anywhere. The boat is new to us so its a bit of a mystery. 

 

Its almost as if there's a blockage in the Tee coming off the stat, but I'm not sure thats even possible given it should be in a constant flow of water.

 

Stu

[Tracy D'arth]

Just now, StuartAdair said:

Thank you for all of your replies. The hidden pipe at the back goes onto a temperature sensor and doesn't flow anywhere. The boat is new to us so its a bit of a mystery. 

 

Its almost as if there's a blockage in the Tee coming off the stat, but I'm not sure thats even possible given it should be in a constant flow of water.

 

Stu

Perhaps Tony  is on the  ball and that swept tee on the flow has been fitted cack handed about face.

[Tony Brooks]

1 minute ago, Tracy D'arth said:

That looks like any other Lister LPW plumbing as I remember it. I thought they had a standard single poppet stat in?

I must be going barmy, I am sure I read Nanni in the OP. On the basis of what you say it certainly sounds like a blockage in the T or adjacent fittings.

 

2 minutes ago, StuartAdair said:

Thank you for all of your replies. The hidden pipe at the back goes onto a temperature sensor and doesn't flow anywhere. The boat is new to us so its a bit of a mystery. 

 

Its almost as if there's a blockage in the Tee coming off the stat, but I'm not sure thats even possible given it should be in a constant flow of water.

 

Stu

 

But if a hose hardens inside chunks of rubber can fall off and block any small pipe with a step in it.

4 minutes ago, StuartAdair said:

Thank you for all of your replies. The hidden pipe at the back goes onto a temperature sensor and doesn't flow anywhere. The boat is new to us so its a bit of a mystery. 

 

Its almost as if there's a blockage in the Tee coming off the stat, but I'm not sure thats even possible given it should be in a constant flow of water.

 

Stu

 

But again if, as the OP says it only goes to a temperature sender, so a stop end, coolant should still pour out with the engine running. However, what temperature sensor is that then. I can see what looks like a temperature sender screwed into the stat housing just behind that T. I suppose one could be an overheat switch though.

[rusty69]

This is the thermostat on our LPW4S. Dunno if it differs from the LPW4

[StuartAdair]

Thank you for all your help. I'm going to have a dig around tomorrow after work. I'll take the stat out and see what I find underneath. Will give you an update as soon as I know more 🙂

[Tony Brooks]

1 minute ago, StuartAdair said:

Thank you for all your help. I'm going to have a dig around tomorrow after work. I'll take the stat out and see what I find underneath. Will give you an update as soon as I know more 🙂

 

That will give you a chance to try to poke through the drilling and fittings in both directions, but the swept T will make it harder to get any sort of wire in one side and out the other.

[jonathanA]

Doesn't look like standard lister canalstar setup to my eyes. A few more pics might help along with the engine build number off the plate on the engine. Looks like the temp sender tapping rather than the feed to cauliflower but if its really a lpw4 rather than a lpsw4 then I'm not sure. If it is the temp sender tap then it might only be 1/8 npte so quite a small fitting to supply a cauliflower. 

[Steve56]

Just a few comments that may or may not help. The engine is not a Canal Star it is heat exchanger model which is why it may look a little different. The T-piece is not a swept T but just a standard T. Oneside is the calorifier feed the other is the temperature sender. The thermostat shown in an earlier post is the one that should be fitted to the later engines as the one in the photo. It is important as it shuts the pump bypass off as the engine warms up.

 

 

[Karen Lea Rainey]

Have you got an on/off valve closed on the pipe to the calorifier or something similar in the pipework stopping any flow of hot water.

If you've only just had the boat, was it all drained down some time ago hence closed valve or air crept into pipes creating a blockage.

[StuartAdair]

All

Thanks once again for all your advice. I took a closer look at things last night. 

Firstly the 'T' piece appears to be just that with a 10mm reducer in the end feeding onto the flow site rubber pipe to the calorifier. The other side of the 'T' goes to what looks like a temperature sender unit with a blue wire on, however the wire was off so I put it back on (Temp gauge was unaffected and works fine).

 

I took the thermostat housing off and found a fair few pieces of stuff that looked like teeth tartar. I removed all that and blew an airline through the T piece and calorifier (A fair amount of crap came out). 

 

Ran the engine up and the water was now flowing through the T and the calorifier pipes started to get hot so hopefully I might have fixed it.

 

I did wonder about fitting a 12v heat resistant pump into that circuit to improve the efficiency of the water moving through the calorifier?

 

Thanks once again

Stu

[Tony Brooks]

1 minute ago, StuartAdair said:

All

Thanks once again for all your advice. I took a closer look at things last night. 

Firstly the 'T' piece appears to be just that with a 10mm reducer in the end feeding onto the flow site rubber pipe to the calorifier. The other side of the 'T' goes to what looks like a temperature sender unit with a blue wire on, however the wire was off so I put it back on (Temp gauge was unaffected and works fine).

 

I took the thermostat housing off and found a fair few pieces of stuff that looked like teeth tartar. I removed all that and blew an airline through the T piece and calorifier (A fair amount of crap came out). 

 

Ran the engine up and the water was now flowing through the T and the calorifier pipes started to get hot so hopefully I might have fixed it.

 

I did wonder about fitting a 12v heat resistant pump into that circuit to improve the efficiency of the water moving through the calorifier?

 

Thanks once again

Stu

Thanks for the feedback & pleased it seem to be sorted.

 

I doubt a 12V pump will make a difference  as long as the calorifier coil stays air free. Until the calorifier has heated the engine thermostat will stay shut or only partially open and that will prevent coolant circulating through the skin tank. That leaves the calorifier and the smaller engine bypass port as the only path for water pump output so the engine water pump will ensure circulation through the calorifier.

[Cheshire cat]

What about the Teeth Tartar? I'm wondering if the engine has been topped up with hard water over the years and is perhaps in need of descaling?

[StuartAdair]

4 hours ago, Cheshire cat said:

What about the Teeth Tartar? I'm wondering if the engine has been topped up with hard water over the years and is perhaps in need of descaling?

Good call. How would I go about descaling ?

[Eeyore]

A few more pictures showing the general arrangement of the pipework and an overall view of the engine will help get you the best advice for your particular installation. Is there a brass coloured pump below the one in your first photo?

[BEngo]

3 hours ago, StuartAdair said:

Good call. How would I go about descaling ?

Get some central heating descaler from Screwfix or its competitors.  Check it is suitable for mixed  metals including aluminium (if there is any in your coolant circuit,) steel, copper and cast iron. Replace all the coolant with the descaler, diluted as instructions for CH  dealing.  Run engine and get it and pipes properly warmed up.  Expect lots of bubbling and gurgling  including possibly overflowing headers.  Don't  go running at high power once it starts working as the bubbles reduce the cooling efficiency.  

 

When it calms down, allow the engine to cool,  drain down, rinse through with fresh water and refill with 25 -30% of a suitable anti  freeze  pre-mixed with water.

 

N

 

[Cheshire cat]

What Bengo said. The descaler instructions should tell you how long to leave it in. I'm thinking half an hour or so.

[StuartAdair]

All,

A further update for you. We ran the boat this weekend and once again the water failed to heat. The guy who moors next to me is a plumber so took at look. With the engine stopped and the calorifier flow/return pipes disconnected we discovered that if the expansion tank cap was loosened then water would flow but then stop when the cap was replaced, so the initial suspicion was a cap causing some sort of airlock in the engine. However when we ran the engine again cap on and off there was very little water flow from the engine outlet, indeed you could stop it with your finger.  After a bit of research I discovered that a water pump should put out about 40psi, and I think I've got about 4 psi on a good day. There's enough to stop the engine overheating but not enough pressure to flow through the calorifier which makes sense to me. 

New water pump is on order so lets see if that does the trick.

 

Stu

Edited August 30, 2022 by StuartAdair

[Bod]

When you have the old and new together, a photo of the water vanes, might be interesting.

 

Bod.

[Steve56]

6 hours ago, StuartAdair said:

All,

A further update for you. We ran the boat this weekend and once again the water failed to heat. The guy who moors next to me is a plumber so took at look. With the engine stopped and the calorifier flow/return pipes disconnected we discovered that if the expansion tank cap was loosened then water would flow but then stop when the cap was replaced, so the initial suspicion was a cap causing some sort of airlock in the engine. However when we ran the engine again cap on and off there was very little water flow from the engine outlet, indeed you could stop it with your finger.  After a bit of research I discovered that a water pump should put out about 40psi, and I think I've got about 4 psi on a good day. There's enough to stop the engine overheating but not enough pressure to flow through the calorifier which makes sense to me. 

New water pump is on order so lets see if that does the trick.

 

Stu

That is what you would expect. When the cap is on it creates a vacuum so the water will not run out easily. When the cap is removed it allows air into the system so the water will flow out. As the pump is not a positive displacement pump it will not pump at any great pressure.I don't know where the figure of 40 psi comes from but the pump certainly will not give those sort of pressures.