if there is no leaks in the rad valves overground ,what is the best way to find out the leak as all the pipes underground,or its better to put new pipes
check the pressure relief discharge pipe (its should be on the outside wall that the boiler is hung on) see if thats leaking
also when you have topped it up check the pressure guage whilst the boiler is running (does it rise really really quickly)
If the above is happening then you need a new expansion vessel and possibly a new pressure relief valve.
if there is a leak under the floor you can use an infra red thermometer to map out the temperatures on the floor, the heating pipes should show high temps in a small cross section and a leak will show a high temp over a bigger section (this is a really hard way of doing it but it does work)
alternatively you can pay a company like MUNTERS 250 and they will attend your property with thermo imaging cameras, it sounds expensive but not as dear has tearing up the screed on your floors trying to look for a leak.
Cheak all pipe work that you can see, also check all rad valves (i doubt its these as you are losing ALOT of water very very quickly)
If the above does not appeal wait the leak will show itself eventually, but may have caused soem considerable damamge before it pops its nose up
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local