Hi, Not sure if this is the right place to ask, I have a 2Kw oil filled electric heater and just discovered a small oil leak from the valve at the bottom where the element goes in, have taken the element out and the washer has perished, so need an new one, the question is do I need a special washer for this or will any plumbing washer do, it is a Honeywell heater and I don't seem to be able to find them, only their central heating division.