macmac Posted June 12, 2020 Share Posted June 12, 2020 Fuse types Whats the difference between a slow blow fuse & a anti surge fuse? We had a new (system) Worcester Greenstar 18 Ri Central Heating Boiler, fitted 8 years ago. It started with a leaking Y valve in the airing cupboard, which is inconvenient, but in the current CV climate it was bearable. The other day the boilers power whent off. I pulled it apart, and followed the fault guide in its installation booklet, which said to start by checking 2 fuses. The first mains fuse inside the boiler, had failed, so I replaced it with a spare that was included inside the boiler. It ran fine for about 5 days, then because the weather was hot (remember that?) I reset the timer to stop the heating coming on in the morning, so now it was just heating the water. Later that day, I went to turn on the heating, and the fuse failed again. I tried a new fuse from my old supply of fuses, and that failed instantly. The book says this fuse is a SLOW BLOW, and it's marked: [F] T2AH250VP My replacement is labeled: T2A / 250 So is my replacement fuse OK ? Link to comment Share on other sites More sharing options...
ProDave Posted June 12, 2020 Share Posted June 12, 2020 T2A usually means time lag. So yes it is the right fuse. So 3 fuses have blown. Time to look for the fault that is causing them to blow. Is that leaking "Y valve" (I assume you mean 3 port motorised valve?) leaking such that any electrical parts of it are getting wet? Or the water dripping on any other electrical items? Link to comment Share on other sites More sharing options...
dpmiller Posted June 12, 2020 Share Posted June 12, 2020 If it's a glass fuse, can you see in still or is it blasted silver/black inside? Link to comment Share on other sites More sharing options...
macmac Posted June 13, 2020 Author Share Posted June 13, 2020 (edited) 23 hours ago, ProDave said: T2A usually means time lag. So yes it is the right fuse. So 3 fuses have blown. Time to look for the fault that is causing them to blow. Is that leaking "Y valve" (I assume you mean 3 port motorised valve?) leaking such that any electrical parts of it are getting wet? Or the water dripping on any other electrical items? Yes, its the motorised valve, I've checked all of the electrical connections, eg: valve, pump, timer & connection box, and they all seem OK. Edited June 13, 2020 by macmac Link to comment Share on other sites More sharing options...
macmac Posted June 13, 2020 Author Share Posted June 13, 2020 (edited) 22 hours ago, dpmiller said: If it's a glass fuse, can you see in still or is it blasted silver/black inside? The body colour of the original fuses was white, and my replacement was green, and they didn't change colour. Edited June 13, 2020 by macmac Link to comment Share on other sites More sharing options...
ProDave Posted June 13, 2020 Share Posted June 13, 2020 8 minutes ago, macmac said: The body colour of the original fuses was white, and my replacement was green, and they didn't change colour. The white one is ceramic and is an HRC (High Rupture Current) fuse which means it can interrupt a high fault current without failing. The glass ones might crack or explode if the fault current was that high. Link to comment Share on other sites More sharing options...
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