Alde comfort Boiler

[fishee]

Can anyone help?  I have an old Alde comfort gas boiler which heats the water in my calorifier & 4 radiators onboard.  I have recently removed 2 of the radiators & capped them off.  There don't seem to be any leaks in the system and I have re-filled the header tank with 50/50 anti-freeze/de-ionised water.  But when I have switched the boiler back on there is no hot water!   I've opened the valves on the radiators to bleed them with the Alde off and on several times and water comes out but it's not heating up!?!  I have tried isolating the radiators and firing up the boiler - the water in the header tank gets hot and the pipe leading to the calorifier gets warm but not hot (I've tried leaving it on for several hours but it still doesn't heat the water in the calorifier)  What am I missing here?

[philjw]

How is the system plumbed up?  It could be the case that the heated water has to pass through the first radiator before going on to the second and subsequent radiators and eventually to the boiler .  This arrangement is different from the domestic norm where the supply to each rad is teed off from a common supply pipe. I'm thinking that now you have capped off some rads there is no supply getting passed the capped off rads.

 

[Graham and Jo]

My boat also has a Comfort boiler. There are two separate circuits, one to the rads which as Philjw says goes from rad to rad to rad before returning to the pump and then the bottom of the boiler, the other goes to the calorifier before returning to the pump and then to the boiler. There are two valves, one in each circuit. One isolates the rads in the summer and the other enables you to balance the flow through the rads and calorifier. 

Now for the interesting point, the pump is connected to the boat thermostat which has to be set above the boat temperature to work and hence heat the water. In this weather it needs to be set to max!!

An alternative idea is that you have an airlock in the calorifier circuit. I bleed mine by disconnecting the output side of the pump with the pump running and the boiler off, the radiator isolation valve closed and the valve in the line from the calorifier fully open.

Cheers Graham

 

 

[Dave Payne]

I have the same system, but i have to use a switch on the wall, this is linked to a separate pump that is inline with the hose from the back of the boiler to the calorifier, do you have this system?

 

I do not have to to touch the heating room thermostat or have hot water running through the rads.

 

[john6767]

1 hour ago, Graham and Jo said:

My boat also has a Comfort boiler. There are two separate circuits, one to the rads which as Philjw says goes from rad to rad to rad before returning to the pump and then the bottom of the boiler, the other goes to the calorifier before returning to the pump and then to the boiler. There are two valves, one in each circuit. One isolates the rads in the summer and the other enables you to balance the flow through the rads and calorifier. 

Now for the interesting point, the pump is connected to the boat thermostat which has to be set above the boat temperature to work and hence heat the water. In this weather it needs to be set to max!!

An alternative idea is that you have an airlock in the calorifier circuit. I bleed mine by disconnecting the output side of the pump with the pump running and the boiler off, the radiator isolation valve closed and the valve in the line from the calorifier fully open.

Cheers Graham

 

 

Good point on the thermostat.  We have the same central heating and when we were buying the boat the survey was done on a day like today, and it was noted that the central heating was not working, as soon as it was colder it worked fine!

If the pipe its hot it does sound like an air lock though.

[Rickent]

We have the same. If the temp in the boat is higher than the max on  the wall stat the water will not heat up.

[IDS]

To test you can bypass the thermostat with a short length of wire across the two wires that go to the thermostat if you can find a convenient connector block (usually near the pump). The pump will then run all the time, whatever the temperature in the boat. Remember to disconnect it after the test.

[cuthound]

It may that that there is too much antifreeze in the system. 

When I flushed and filled my CH system (Webasto boiler) with a 50/50 mix, it no longer got hot, although the boiler did.

On the advice of this forum's NMEA, I diluted the system to 75% water/25% antifreeze and hey presto, it all worked normally agian. 

[Graham and Jo]

41 minutes ago, cuthound said:

It may that that there is too much antifreeze in the system. 

When I flushed and filled my CH system (Webasto boiler) with a 50/50 mix, it no longer got hot, although the boiler did.

On the advice of this forum's NMEA, I diluted the system to 75% water/25% antifreeze and hey presto, it all worked normally agian. 

That is interesting, I was advised by Alvechurch (when we bought the boat) to use 40% in the rads and 30% in the engine. There is an article here supporting the concept of lower percentages being more efficient.

Cheers Graham

[cuthound]

31 minutes ago, Graham and Jo said:

That is interesting, I was advised by Alvechurch (when we bought the boat) to use 40% in the rads and 30% in the engine. There is an article here supporting the concept of lower percentages being more efficient.

Cheers Graham

I replaced the engine coolant and CH system with a 50% solution of Ford Premium Longlife antifreeze, because it lasts 10 years and it's a pain in the backside changing it every 2 years with ordinary blue antifreeze.

Then as I said in the previous post, the CH didn't work until I weakened the solution. 

A stronger solution offers better corrosion resistance and will freeze at a lower temperature, but costs more and is no use if the heating won't work 

[dor]

15 hours ago, cuthound said:

It may that that there is too much antifreeze in the system. 

When I flushed and filled my CH system (Webasto boiler) with a 50/50 mix, it no longer got hot, although the boiler did.

On the advice of this forum's NMEA, I diluted the system to 75% water/25% antifreeze and hey presto, it all worked normally agian. 

This was probably due to incomplete mixing of the antifreeze.  The rads depend on a very slight density difference in the water to circulate inside the rad.  If the antifreeze is not completely mixed, then the density difference can block the circulation inside the rad.

I had this once, even though I was only using about 30% antifreeze.   Several of the rads didn't get hot.  I drew out a few litres of water through the bleed valve and mixed it back in and it was then fine.

Mix your antifreeze well with the water before filling the system.

[Tony Brooks]

18 hours ago, IDS said:

To test you can bypass the thermostat with a short length of wire across the two wires that go to the thermostat if you can find a convenient connector block (usually near the pump). The pump will then run all the time, whatever the temperature in the boat. Remember to disconnect it after the test.

The Alde ones have three wires so double check which two to bridge.

 

20 hours ago, Dave Payne said:

I have the same system, but i have to use a switch on the wall, this is linked to a separate pump that is inline with the hose from the back of the boiler to the calorifier, do you have this system?

 

I do not have to to touch the heating room thermostat or have hot water running through the rads.

 

Now that sounds a neat solution. Next question - where can I fit this extra pump? - I mean physically, there is not much space where my pipes run.

[Dave Payne]

16 minutes ago, Tony Brooks said:

The Alde ones have three wires so double check which two to bridge.

 

Now that sounds a neat solution. Next question - where can I fit this extra pump? - I mean physically, there is not much space where my pipes run.

Ill take a photo and stick it up when i get chance, its always puzzled me how it works, it must have different connections on the back of the boiler to the central heating?

 

 

[dor]

42 minutes ago, Tony Brooks said:

The Alde ones have three wires so double check which two to bridge.

 

Now that sounds a neat solution. Next question - where can I fit this extra pump? - I mean physically, there is not much space where my pipes run.

On my current Alde 3010, I just used a switched supply straight to the pump, with a red LED to remind me it is on (which also comes on when the controller switches the boiler on, useful to remind me the heating is running).  I did something similar on my previous boat which was a Comfort 2928.

Edited to add:  Just realised, I did this just to run the pump, so I could use the calorifier to act as  a heat exchanger.  To get the boiler running to just heat the calorifier I just turn the thermostat up.

Edited June 21, 2017 by dor

[Tony Brooks]

The boiler itself has its own boiler stat to control the boiler temperature. This is independent of the room stat that only controls the Alde pump.

The switch on the room stat simply supplies power to the boiler for the ignition and pump. Once the boiler has fired up I  do not think it needs any power for the burner or burner control. The boiler stat seems to be mechanical.

I suspect that your extra switch just turns the extra pump on and off although it may also provide an alternate supply to the boiler for ignition.

 

Now - being a clever cloggs - This winter I decided to rewire my Alde. I find the slide switch on the room stat a pain so I took that out of circuit. I added a centre off three position double pole switch. One on position feeds the boiler on one pole and connects the room stat to the boiler pump by the other. The second on position feeds the boiler on one pole and connects a cylinder stat to the boiler pump by the other pole. There is also a two way change over valve to isolate the radiators when I juts want hot water.

Feeling very smug it all seemed to work BUT for some reason the cylinder stat does not seem to work/get hot enough to turn off the boiler pump. Hence my liking the idea of an extra pump and controlling the water temperature by the boiler stat.

[Dave Payne]

A quick google brings this up, is it an addition then to the standard boiler?

 

https://caravan-parts.store.buegle.com/product.php/hot_water_heater_2957/?k=:::1645863

 

[Tony Brooks]

I think its basically a mains immersion heater add on but it will probably store some hot water if you did not have a calorifier.

[Dave Payne]

I wonder if its a combi style set up then, at the minute the pump forces the hot water through the calorifier tank coils, if you connected the outlet to a tap via a pump with built in switch, would it kick out instant hot water, then stop when tap turned off?

[cuthound]

4 hours ago, dor said:

This was probably due to incomplete mixing of the antifreeze.  The rads depend on a very slight density difference in the water to circulate inside the rad.  If the antifreeze is not completely mixed, then the density difference can block the circulation inside the rad.

I had this once, even though I was only using about 30% antifreeze.   Several of the rads didn't get hot.  I drew out a few litres of water through the bleed valve and mixed it back in and it was then fine.

Mix your antifreeze well with the water before filling the system.

Nope, the water and  antifreeze were premixed before putting it into the system, so it wasn't that.

I even tried to get a thermosyphon going by heating each radiator in turn with an electric hot air paint stripper. This got the radiators working correctly, but the system revered back to not working each time it had cooled down and had to restart from cold.

Eventually NMEA suggested reducing the concentration of antifreeze from 50% to 25% and since then everything has worked perfectly.

 

[fishee]

Thank you all for your replies.  I'm learning a lot.  I have also just spoken on the phone to Graham Cutmore (recommended by Alde) and yes, it would seem I need to switch the room thermostat on, and turn it up to it's maximum (this recent hot spell didn't work in my favour) to kick start the pump on the header tank.  I will give that a try this evening when I get to the boat.  Fingers crossed.