

💧 Stop leaks before they stop you — the smart fix for flawless heating
The CW4 Central Heating Leak Sealer is a super concentrated, metal-safe, and eco-friendly solution designed to seal minor leaks and fix pressure loss in central heating systems. Treating up to 18 radiators or 150 litres, it works without system shutdown and remains permanently in the system, saving costly repairs and downtime while protecting your boiler and the environment.







| ASIN | B088JYB6JZ |
| Batteries Required? | No |
| Batteries included? | No |
| Best Sellers Rank | 326,032 in DIY & Tools ( See Top 100 in DIY & Tools ) 3,167 in Sealers |
| Customer Reviews | 4.0 4.0 out of 5 stars (531) |
| Date First Available | 12 May 2020 |
| Item Weight | 453 g |
| Manufacturer | CosWarm |
| Manufacturer reference | CosWarmCW4 |
| Package Dimensions | 18.2 x 8.6 x 5.8 cm; 453.59 g |
| Part Number | CosWarmCW4 |
| Size | 500ml |
R**M
Did the job!
We had a very small leak on a radiator valve and bought this to see if it would stop the leak rather than draining the system and replacing the valve. It worked a treat and no more leak.
K**.
Works well
Kept losing boiler pressure due to small leak under floor. A few days after treatment the pressure is fine.
A**R
OK for small pressure loss,but sadly no help for me.
Leak on garage radiator tap.
A**A
Central Heating fluid.
My husband was very pleased with this item.
A**S
Unfortunately this did not work for me,
Still losing pressure over the space of a week, have a large heating system added two bottles
A**.
Didn't use it
I bought this as the water pressure kept dropping in my boiler and I could not find the reason. This was suggested for treating small leaks in hard to find places. However, the day after I ordered it I found the leak and after speaking to a plumber this was not going to help. One thing I would say is that it is only the bottle is supplied and I couldn't work out how to get this into the heating system. Looking else where you are probably going to need some sort specialised funnel.
A**R
Leak sealant- stopped the leak
Used for a very small leak on bathroom radiator union pipe. Worked first time. Pour in, run heating, seal leak. What’s not to love?
D**R
Really works
This product really works, had a small leak in boiler and had to top up every 2 days. it sealed the leak within 2 hours.
R**Z
Esta es su ventaja más importante: impide eficazmente que el agua, el aire, el polvo, los insectos y el ruido pasen por los huecos.
V**E
Excellent produit Ça a fonctionné du premier coup Pour un trou dans un radiateur en acier Super je recommande
T**O
Mijn vloerverwarming had een lekkage, wist niet of dit ook geschikt was voor vloerverwarmingsslangen maar daar lijkt het wel op. Na dit middel te hebben toegevoegd hebben wij geen drukverlies meer. He wel voor de zekerheid de slangen goed doorgespoeld met schoon water voordat ik het erin deed.
M**A
Un prodotto eccellente per riparare micro-perdite e stabilizzare la pressione degli impianti di riscaldamento. La formula concentrata tratta fino a 18 radiatori ed è compatibile con tutti i metalli, alluminio incluso. Soluzione professionale, sicura e facile da gestire. Consigliatissimo per la manutenzione.
W**G
I have a 24 rooms motel with a 20 years old boiler, add few bottles cw4 and cw1 , no more leaking. Thanks a lot. from Alberta canada.
Trustpilot
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