Chemical stores containing a water heater, what could go wrong?

Hi fellow techies I need some advise please. We are having building work taking place within the Science department. They have removed 2 chemical stores where the majority of the chemicals are stored and left me with one half sized store and one other small store which houses the water heater for the Prep Room. My question is what type of chemicals can I store next to a water heater? Also neither stores currently have any kind of extractor fans or lights in them. Do I need to ask them to put extractor fans in? Its a real mess, with no consultation. I'm fuming.

I will be trawling through the CLEAPSS chemical safety documents this afternoon.

Thank you lovely peeps
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Yes you need a extractor for LEV, ours is tested annually.

It should also be spark free fittings inside if you have flammables in there, we just have under sink water heaters everywhere (stored hot water probably has legionella regs).

We also just had vents put in the doors. (the vents should have intumescent inserts that close when there is a fire.)
The vents in the doors should also be at the bottom. And the extract near the top and as far away from the door as possible. Minimum of 2 air changers per hour. If they object then remove all "smelly" chemicals for disposal :- ammonia, propanone, pet spirit, hexane heptane etc see how the chemistry teachers react to the reduced list.
That sounds like a major problem waiting to happen, if the water heater ever leaks! Bringing CLEAPSS in to point politely but firmly at the riot act seems like a plan at this point, there's all manner of wrong this about what you describe.
Hi, I visited the department yesterday and the chemical store will have new extraction fitted :)The pipework will be boxed in and the door will have a vent. But the wall housing the water tank is damp. I was told that it won't be completed until April, even though our kids are back from March the 8th! I will be contacting CLEAPSS about this after I've read Section 7 of the handbook. Thanks for the support.
Yes, you absolutely need ventilation/extraction in the chemical stores, otherwise fumes build up over time. As for the water heater, anything potentially flammable or oxidising should be put as far away from it as possible as a general rule. Also make sure group 1 metals (Lithium, Sodium, Potassium) are nowhere near it in case you get any leaks.
Indeed you shouldn't, but it sounded like doing away with it might be a difficult thing to get around. My precautons were given in lieu of the ideal of no water heater being present.