Heating Problem

[Bewildered]

I am hoping someone can help

I picked up my new boat from Daventry, just before Xmas, and spent a week cruising it down to Harefield.

It is a 70ft cruiser stern about 16 years old.

Everything on board seems to function ok except for the heating.

It has a morso squirrel with a back boiler and several radiators. I found some hand written instructions in one of the draws (presumably written by one of the previous owners) stating that the circulation pump needs to be switched on prior to lighting the stove.

When switched on the pump whines and squeals; next to the pump is a variable potentiometer mounted in a single gang electrical patris plate, when turned this affects the pitch of the squealing pump. I assume that this is a variable speed control for the pump that acts as a voltage regulator.

The pump is a Johnson CM-10P-7 12volt

During my journey down we turned on the pump and lit the fire. The radiators did not get hot.

The next day I decided to top up the header tank. This took a great deal of water. I bled the radiators until water trickled out at the top. Lit the fire again but still not heating the radiators.

The amount of water the system took led me to thinkthat the system had been deliberately drained. Why this should be I do not know. Perhaps the pump failed and the last owner did not bother to get it repaired and just decided to drain it.

There are two electric oil filled radiators on board and as the boat has a 5 KVa generator off of the engine I thought perhaps that this was used for heating on days when the stove is not needed.

I think the boat at one time had a diesel fired heating system (possibly tied into the same radiators) as there is space in the engine bay on one side of the counter and a disused diesel pipe coming out of the tank. (Maybe it broke and rather than fix it the oil filled were fitted)(There is also a capped of water pipe next to the pump which is located just behind the front steps)

First of all is it bad for the stove to light the fire if the pump does not run?

I found the pump on line and it is about £140. I was thinking that the best thing to do is to drain the system and take the pump out and try it in a bowl of water to find out if it actually pumps. The problem is that with just a pipe connected into a bowl of water there is no pressure for the pump to push against so it may seem that it works but when fitted back to the system it just isn’t up to task.

So should I just bite the bullet and by a pump anyway?

 

Your thoughts on this would be appreciated

[Dave Payne]

Would have been drained down over winter to stop freezing pipes.

[WotEver]

Would have been drained down over winter to stop freezing pipes.

And a squealing pump often means it's running dry while it burns out the impeller.

[IDS]

The pump spec says it is good for dry running up to 30 mins, if it is still making some noise it is probably still running. If you drain it down inspect the pump chamber for obstuction.

Prime culprit for no circulation is an air lock somewhere. Inspect the pipe runs for possible air traps.

[MtB]

A pump can also squeal if a bit of debris gets caught in the impeller. I'd take it out and inspect and test it before shelling out on a new one. Fit some isolator valves too when you put it back so you don't have to drain down next time.

[wonderdust]

If it is the pump get yourself a couple of 12V/24V Hot Water Circulation Pumps, one as a spare, of ebay or somewhere like that, cost about £15, there quite and there a few owners on here that use them.

[ditchcrawler]

Those pumps if they are not mounted at the correct angle can sometimes get an air lock in them. If its connected by flexible pipes try giving them a good squeeze, that may shift it.

[freddy]

hi,i think you have bought my old boat which i sold in september 2013 if you pm me i will gladly talk you through it.

cheers john

if you send me your mobile no i will ring you

Edited January 12, 2016 by freddy

[Bewildered]

Thanks for all the advice.

Personally I think the pump is knackered, I know I ran it for more than 30 mins the first night I lit the stove. And also ran it the next day after I filled the system, when the squealing became more, well let's say "aggressive".

I have had a look on eBay, as suggested by Wonderdust, for a cheaper replacement; however there are plenty to choose from and I'm not sure which would be the best option. If someone could post a link to a suitable replacement it would be much appreciated.

 

Love the advice from Mike the boiler man to fit the isolator valves. Why this isn't done as standard I don't know, it is so logical and not exactly expensive. I mean really how much can two valves cost £10-£20 not exactly bank breaking is it?

 

And John yes it is your old boat PM sent

[Neil Smith]

You don't have to drain it down over winter as the heating system should have a 25% anti freeze mixture in it to stop freezing and just as important stop corrosion.

 

Neil

[IDS]

If you fit isolation valves, make sure they are "full bore", cheaper ones usually are not.

[Dave Payne]

You don't have to drain it down over winter as the heating system should have a 25% anti freeze mixture in it to stop freezing and just as important stop corrosion.

 

Neil

 

 

But if put on brokerage would they be interested in this, default would be to drain all down?

[Bewildered]

Well today I had a mate who is a plumber come down to the boat to take a look. We topped the system right up and bled it thoroughly but the pump is still not pushing the water around the system. Conclusion it needs a new pump.

 

I spoke to John today who used to own the boat and he told me that when he first bought it, it had a domestic 240v pump fitted.

 

! told this to my mate (who is not really used to doing boat plumbing) and he suggested putting in another 240volt pump connected to a pipe thermostat to automatically switch it on when the pipes behind the boiler get hot.

 

The only down side to this is that the inverter will need to be constantly on in during winter when the fire is lit. I can't really see this as a problem as the boat has 4 very large leisure batteries. and I'm bound to have something else on the boat running 240.

Of course the inverter itself will draw some power.

 

The boat also has no freezer. It does have a 12v fridge. I was wondering weather to buy a cheap small 240v freezer as the cost of 12v is ridiculous. If this were the case the inverter would be running 24/7

 

Your thoughts please.

[ditchcrawler]

Unless you buy an expensive 240 volt pump it will draw a lot more current from your batteries than a 12 volt dc one will.

[Bee]

Without seeing the pipe runs and the whole thing its difficult to know what is, or could be happening but lighting the fire would concern me, its unlikely to go bang if the contents of the back boiler can expand up one or both of the pipes but I would not be very relaxed sitting near it.

[Markinaboat]

You could buy a very low power inverter dedicated to the pump. The current draw would be negligible when compared to a sizeable inverter. Also, not sure if already mentioned above but us there a bleed screw on the 12v pump. Bolin pumps have one and the tiniest smount if air in it will stop circulation completely. Of course, the pump should be on the return and close to the stove (1-2 metres away).

[ditchcrawler]

You could buy a very low power inverter dedicated to the pump. The current draw would be negligible when compared to a sizeable inverter. Also, not sure if already mentioned above but us there a bleed screw on the 12v pump. Bolin pumps have one and the tiniest smount if air in it will stop circulation completely. Of course, the pump should be on the return and close to the stove (1-2 metres away).

I have a Johnson and there is NO bleed screw on it, but as you say a tiny amount of air will stop it pumping. I understand you can take them apart and have seen details online somewhere. A mains pump like a Grunfoss could well be drawing over 4 amps from the 12 volt system so could be one battery full per day.

[Bewildered]

Thanks for all the advice guys.

Unfortunately I am still having problems.

 

A mate who is a plumber took a look at it and decided that after re filling and bleeding the system over and over it needed a new pump.

 

I bought a LF Bros pump which stated that it has a flow of 10L/min and a lift head of 2M

We fitted the pump bit still it doesn’t circulate.

The water at the top of the boiler is hot but it just doesn’t flow around the system (just turns to steam if the valve on the outlet is bled while the fire is lit).

 

Today my mate came back with a big 240volt chemical pump cleaner that he uses to flush out domestic heating systems. He connected it in place of the pump and tested the flow in both directions and found that it flows ok.

 

We reconnected the circulation pump. Re-bled the system and still it is not circulating.

 

My boat is a 70footer. The pump is located behind the front steps the stove is to one side about 2 meters from the front. There are 3 radiators along this side of the boat and a single radiator in the bathroom the other side. The pipes for the bathroom radiator may well travel to the back of the boat and then a 3^rd of the way back towards the front. The header tank is outside just behind the rear bulk head on the cruiser deck.

All the pipes are run at floor level so there is no help from gravity and the pump has to do all the work.

We have checked the pipe layout from the stove to the pump and the pump is on the return pipe.

Although the hot pipe does tee off under the stove, one direction feeds the rads and the other is capped off near the pump. I believe there was originally a diesel system adjacent to the front door at one time so this odd pipe may have been something to do with this.

 

 

We are at present thinking that we need to fit a bigger pump? Due to the length of the boat (about a 60foot run one side added to about a 20foot run the other).

 

My mate is suggesting a 240volt secondary circulation pump (this is the sort of thing he is used to)

The boat did have a 240volt pump on it several years ago as pointed out to me by John who used to own it

The boat has 4 large leisure batteries and a 600watt inverter. It has two large solar panels and a 5Kva generator built onto the engine. It also has two battery chargers. So replenishing the batteries shouldn’t be a problem just a potential pain in the bum.

 

So the question is; is there a heavy duty 12volt pump that anyone can recommend that will drive this system (I think Johnson do some bigger than the CM10p7-1 that was originally installed) or should I just put in a 240volt that I know would do the job?

 

Your thoughts will be greatly appreciated

[nicknorman]

10l/min is loads, although perhaps 2m head is not that much. But it should circulate the water. Centrifugal pumps don't pump air, are you sure the pump is full of water and not, for example, at a high point in the system that might remain full of air? Are all the lock shield valves and any other radiator valves all fully open?

[Bewildered]

10l/min is loads, although perhaps 2m head is not that much. But it should circulate the water. Centrifugal pumps don't pump air, are you sure the pump is full of water and not, for example, at a high point in the system that might remain full of air? Are all the lock shield valves and any other radiator valves all fully open?

All radiator valves are fully open.

The pump is less than 6 inches above floor level

The system has been bled at all points over and over agian

[Alan de Enfield]

All radiator valves are fully open.

The pump is less than 6 inches above floor level

The system has been bled at all points over and over again

 

Just an observation / question

If you have bled it a number of times then it must be getting air into the system somewhere.

Is that the problem ?

[Tony Brooks]

All radiator valves are fully open.

The pump is less than 6 inches above floor level

The system has been bled at all points over and over agian

 

Any chance of a photo of the pump in place? many 12V pumps have inlets and outlet in positions where unless the pump is vertical it is all too easy to trap air in the pumping chamber. Does the pump have a bleed point on then pumping chamber itself?

[Bewildered]

 

Just an observation / question

If you have bled it a number of times then it must be getting air into the system somewhere.

Is that the problem ?

No we keep bleeding because it wont bleedin' work. Only getting water out. Except on the valve on the hot out behind the stove which we are getting steam due to lack of circulation.

 

After Nickomans post I sent a text to my mate pointing out that as the pump will not run with air in it; I wondered as I cannot see a way to prime the pump, if we disconnected one of the rads and fitted his chemical pump in place then pumped in both directions to prime the circulation pump we could then switch it on and see if it pumps back into the chemical pump, which has a large clear plastic bowl on it.

He thinks it is doable; is this worth trying?

My entire problem could be down to priming the pump.

[WotEver]

Definitely worth a try. It has to be something basic like that.

[Bewildered]

 

Any chance of a photo of the pump in place? many 12V pumps have inlets and outlet in positions where unless the pump is vertical it is all too easy to trap air in the pumping chamber. Does the pump have a bleed point on then pumping chamber itself?

The pump is vertical with the inlet and outlet at the bottom (one underneath and one on the side) there is no bleed point on the pump.