Anybody know about coal fires? Why are we melting grates?

hethmar

Have you tried looking online? Also our local coal merchants sell grates and other fireside bits and pieces, you could ask them which grate to use?

manda1205

Thanks hadn't thought of asking them. Worth a try.

never_enough

I've never heard of a grate melting & wonder if it's a quality issue as my mother spent £70 something on a grate a few years ago. I've never used, or indeed heard of, Taybrite but you seem to be using a lot of it every day, so maybe it burns much hotter than ordinary coal? I've never had to replace a grate & our current one is over 80 years old. We mostly burn coal & logs. Have you asked your coal merchant?

never_enough

As a previous poster has said open fires are very inefficient. With the amount of coal you're getting through you might be warmer, for a similar cost, by blocking the chimney & using an oil filled radiator. You can buy a thing called a chimney balloon to block it off, but in the past I've just filled a bin bag with bubble wrap & shoved it up the chimney.

Errata

manda1205 wrote: »

Thanks very much for the offer, I've just had a look on their website, they seem to sell house coal in 10kg bags for £3.99. ATM we buy Taybrite in 25kg for £7.20. But a bag of Taybrite lasts around 4 days. Im pretty sure a 10kg of house coal would easily go in a day. So for cost will stick to the taybrite, just gotta find someone who does real strong grates I spose! :rolleyes:

From memory, that's about the amount we used. It could be that the grates that are being sold nowadays are imported and not as good as the ones made in this country when most people had open fires. Have you thought about an all night burner ? They're much sturdier all round.

hethmar

I think you will find its a combination of a poor grate and the smokeless fuel which is very fierce.

withabix

This is caused by a combination of a strong draw on your chimney (causing fast and very hot burning as you have described), burning a fuel with a high calorific value (smokeless fuel) and build-up of very hot ash.

Your smokeless fuel has a higher calorific value per kg than natural coal, as it has been heat treated to drive off the impurities (which are normally produced from coal as smoke - which is often yellow due to high sulphur content)

Your grate is a casting and was manufactured in a furnace (= a hot fire).

Every time you heat up your grate, the crystal structure in the metal (steel/iron) changes. When the metal heats up and then cools down, they crystal structure of the metal changes. Each time this happens, your grate will get weaker.

The hotter your fire, the more the crystal structure of the metal will change and the shorter life you will get out of the grate.

From a 'physics' perspective, the best thing you can actually do to prolong the life of your grate is to put your fire out with water, as this results in smaller crystals within the metal, which are stronger.

However, you can't do this, as this will of course result in a black room!

The only thing you can practically do to prolong the life of your grate is to burn fuel with a lower calorific value - standard coal, wood, peat etc.

Due to the way heating and cooling affects a cast metal grate, they WILL have a limited life unfortunately - they will not last forever.

suki1964

We get through a grate every couple of months in the bar I work in - mostly cos most the staff wont clean it out in the mornings and because we have it burning constantly 12 -16 hours a day for about 10 months of the year ( very big fire)

manda1205

Thanks everyone for your replies, particuarly withabix, brilliant explanation!
As for blocking off the chimney, no way! When we first moved here, the previous tenant didnt use the fire, he just used electric heaters. So we gave it a go, this lasted roughly 2 days. We were freezing, the heaters were going flat out and still not managing to heat the living room. We live in a 3 bed semi house, with 2 double glazed windows, the rest are wooden. The fire is the only way to give continuous cheaper heating downstairs.
I do think our best bet is to install a multi-fuel burner, but as I said above, cost atm is a big issue so will have to wait.
I think I'll definitly ask our coal man about a grate, and try to burn a bit more wood rather than coal to see if that helps too.
Thanks again everyone!

hethmar

Its not the coal that is a problem, its the smokeless fuel.