Jump to content

Finding mystery leak in central heating system.


Featured Posts

7 hours ago, ditchcrawler said:

Reading about your bleeding above needing the pump off, doesnt the autovent let air in when the pump sucks. I have an upstairs radiator in the house that does the same thing and considered an autovent but thought it may make matters worse.

Here at home I can only bleed the radiators in the attic with the pump off. With the pump running I suspect the bleed valve lets air in, and the radiators air lock.

Link to comment
Share on other sites

  • 1 month later...

Returning to this topic.  Just put another 4 litres of coolant into the system so there is definitely a leak.  Have looked at all the pipes I can find and there is no visible leak.  There is no water in the bilge.  In the summer before the diesel heater was on, the level in the header tank stayed constant. 

 

Any ideas where else to look?

Link to comment
Share on other sites

On 09/12/2021 at 09:15, frlrubett said:

 

Oh interesting.  I did wonder about the this.  The original gravity system did have a thermostat and a circulating pump on it, so just assumed that a Diesel pumped system would bolt on.  Yes there is an overflow, but that is at the top of the header tank.  Once the level drops below that then I do not know how any liquid will dissipate. 

 

 

 

Out of interest, if the previous system had a circulating pump in what way was it a gravity system?

Link to comment
Share on other sites

11 hours ago, frlrubett said:

Returning to this topic.  Just put another 4 litres of coolant into the system so there is definitely a leak.  Have looked at all the pipes I can find and there is no visible leak.  There is no water in the bilge.  In the summer before the diesel heater was on, the level in the header tank stayed constant. 

 

Any ideas where else to look?

 

If you can rule out evaporation and leaks in the pipework and rads then all that is left is a leak from the heat exchanger, when hot, into the exhaust gasses where it will evaporate and apparently disappear. I have no idea how you can find this apart from doing a bench pressure test on the boiler using just off boiling water. I have no idea what  a safe test pressure would be but as some use these boilers on a pressurized system I think 1 to 2 bar would be OK.

Link to comment
Share on other sites

How about:

Somewhere in the system there is one or more points where expansion of the components when heated (and only when heated) causes a tiny leak or leaks.  The leaking water is evaporated off by the heat of the adjacent components, so no water is visible or feelable.  

This would lead to higher humidity in that area of the boat and possibly condensation depending on the level of ventilation, and possibly staining around the leak point(s), and a drop in tank levels but only when heating is used.

Link to comment
Share on other sites

On 08/12/2021 at 23:36, frlrubett said:

First winter aboard this boat and initially the central heating (three rads, towel rail and calarofier) were fed by a gravity system into a stove back boiler with thermostat. 

 

As this was noisy, inefficient we decided to remove the back boiler and fit a diesel heater.  We had coolant loss from the system quite a bit but I attributed that to getting the stove too hot to quick, happened quite regularly, could hear the water boiling in the pipes.

 

Now the stove has gone, the diesel heater installed and I have just checked the header tank again.  It was empty.  Have refilled with four jugs of pre mixed coolant, I guess about six liters.  Have spent the whole day looking for a leak but everything looks dry. There is a hole at the back of the boat, under the floor where you can see/feel the bottom of the bilge and that is also dry.

 

- this boat was built in 2011, I would assume any leak would arrive at the rear of the boat at the lowest point on the bilge?  We list to the rear, especially with an empty water tank so I any leaks would collect back here.

 

- Would a leak of this size be obvious?  I have checked around all the radiators and joins in the pipes which I can see. Around the heating pumps and calorifyer. 

 

- how else can I go about finding this leak, I am sure that losing six litres is definitely a leak?

 

Thanks

 

I might have missed this but how many times have you refilled the new diesel heating system? I only ask because on any new system which had just been filled one would expect the coolant level to drop after first use as any voids are taken up by coolant and rads are bled. Of course if it's losing fluid constantly then ignore what I've just said.

 

I recently installed a reconditioned Webasto into an existing/modified C/H system and I'm finding that every month I need to bleed the first rad in the system because the top quarter isn't getting hot. I can't work out where the air is coming from? 

Link to comment
Share on other sites

1 minute ago, system 4-50 said:

How about:

Somewhere in the system there is one or more points where expansion of the components when heated (and only when heated) causes a tiny leak or leaks.  The leaking water is evaporated off by the heat of the adjacent components, so no water is visible or feelable.  

This would lead to higher humidity in that area of the boat and possibly condensation depending on the level of ventilation, and possibly staining around the leak point(s), and a drop in tank levels but only when heating is used.

This makes sense.  Seems to be quite a lot of water lost though, the diesel heater runs about 90 minutes a day.

1 minute ago, blackrose said:

 

I might have missed this but how many times have you refilled the new diesel heating system? I only ask because on any new system which had just been filled one would expect the coolant level to drop after first use as any voids are taken up by coolant and rads are bled. Of course if it's losing fluid constantly then ignore what I've just said.

 

I recently installed a reconditioned Webasto into an existing/modified C/H system and I'm finding that every month I need to bleed the first rad in the system because the top quarter isn't getting hot. I can't work out where the air is coming from? 

I think this is the second time I have added 3/4 liters of water since the heater was installed.  Rads bled also - a big air lock working its way out slowly?  Lets hope!

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.