Using a different approach according to business type is advisable, even if it's only a very smnall change in the text. Understand the needs of your customers too. There is no "out of hours" in nursing care, the residents live there 24/7! The best time to clean is daytime hours, after breakfast and before tea.
Be careful about promising odour "removal", odour "control" is more appropriate in nursing homes. Try getting the smell of urine out of your machine and hoses after cleaning the carpets and you'll understand why! Emphasise the health aspects for these customers, as well as maintenance cleaning making carpets last longer to minimise the upheaval involved in replacement.
Yes, you need a name, don't put Sir/Madam cos it'll get binned straight away. Don't address to "the manager" or anything other than a person you know the name of. It's generally accepted that telephoning a list of prospects is the first way to make contact, as you cut out wasted time and effort sending letters to nameless people or those who wouldn't be interested.
I wouldn't waste my time and money sending flyers to commercial customers, they won't reach in and touch the right person. You need a personal contact in my opinion.
No offence meant, but your letter isn't very engaging and doesn't come across as if a lively, interested person has written it. It's very generic and just lists lots of features. "Features tell, benefits sell" is a commonly used saying in marketing. Tell them what they're going to get out of it and why only you can give it to them.
Our powerful equipment removes much more moisture from the carpets than conventional equipment, resulting in very fast drying times - typically under one hour. This means that rooms can be used again very soon after cleaning, causing minimum disruption to your staff and residents.See how that's much more of a sales tool than a bullet point that says "Fast Drying" ?
I can thoroughly recommend this book, which is very simple to understand, and relays some of the basic marketing principles without complicated BS:
www.amazon.co.uk/Complete-Guide-Quick-Marketing-Works/dp/0566078384/ref=sr_1_2?ie=UTF8&s=books&qid=1217959756&sr=1-2