We have an annexe that we let out - currently the hot water and central heating are fed from the main house, and the rent includes these. That system doesn't really work.
We want to isolate the annexe from the main house and provide it with self-contained hot water and heating systems. The space heating we can take care of with electric heaters - it is the hot water system I am not sure about.
The annexe has a bath, shower, and basin in the bathroom, plus a sink in the kitchen. We have no mains gas.
I spoke to a plumber who said a "megaflow" water tank was the best bet. But then he told me the price, and its scary - £900 approx plus fitting.
Are there any other options? What sort of water heating systems should I consider?
Mainly because its very expensive and causes tension. What we find is that the tenants have the heating maxed out especially at weekends and use tons of hot water. The main house is fairly big, and is fed from an Worcester oil combi boiler. This eats oil - and yes, I have it serviced regularly. Its impossible to divide up the bill and say who used what.
We are trying to economise and in our house we prefer to only have the hot water and heating on for a couple of hours a day.
My feeling is that if people pay for what they use then they can make their own decisions about how warm they want to be, how much hot water they want to use, and how much they want to pay. On the other hand if they are paying a fixed sum as at the moment then they just max it. Who wouldn't?
So we want to isolate the water an space heating in the annexe so tenants can make their own choices. I don't want to rip anyone off, but I would like people to pay for what they use.
If you want showers, you either need very high tank, a pump, or a mains pressure system.
A mains pressure tank uninstalled is, by dint of safety considerations, always going to be £600 or so. If you choose a simple unpressurised tank you need to add £200 of pump to that to get shower pressure, and the cost of a header tank as well. As well as somewhere to put it and the plumbing that goes with it.
you might think that you can get away with a tank with built in header. Well you probably cant, since the header is so small that it will run dry at pumped shower rates.
Oh, and the other thing to consider is water softening if in a hard water area. I have just finished reconditioning 400 quids worth of shower mixer for my inlaws, only to discover the pump that drives it has gone phut. The main cause of the original problem was scale. Thst about
600 quids worth of kit that any normal plumber would simply have replaced. None over ten years old.
Here I spent £500 on a softener, and about £5 a month on salt, but we find that a large bar of soap lasts about a YEAR for two of us..and none of the plumbing or taps have gone in the last 6 years since the system was installed.
Its up to you whether yu want to trade a few pence for an unsatisfactory system that wont last, or do the job properly.
More and more I find that if a job is worth doing at all, its worth doing properly.
You want to aim for a low maintenance quality system. And expect that the capital cost will repay itself in terms of trouble free operation.
Or an instantaneous electric shower. I know they're not as good as a pumped or mains pressure stored system, but in a rented property a 10kW shower is likekly to be acceptable to most tenants. Especially if there's a bath as well. However you then have the cost of installing a new electric shower, which if there isn't a spare way in the CU might need a new CU or a henley block etc...
So, are you intending a separately metered electric and/or gas supply? (Does the annex have any gas in it at the moment?)
Standard rate electric heating won't be very attractive to tenants unless the annex is insulated to very high standards (and I believe you have to start providing details such as typical cost of heating to tenants shortly).
Indeed - and with rising energy prices it's not easy to be fair to both sides. Their own heating system (and presumably a reduction in rent) removes the arguments.
Instant electric heating simply isn't practical. So if you must use electricity you're down to some form of storage system. As you've discovered, mains pressure ones are pretty costly - so would it be possible to fit a header tank? If so, you could then use a conventional cylinder and immersion.
Other way might be an instant heat Calor gas multi-point.
Creative and much more efficient solution: you're happy to solve the space-heating issue using electric heaters. For hot water, supply them from your existing combi, but put a water meter on the hot-water supply pipe into the annex and agree on a price per litre which you put in the tenancy agreement. The cost will be negligible by comparison and the job is easily DIYable. Also you are not increasing the amount of stuff which you have to maintain and which may break down.
Ordinary meters aren't usually capable of measuring water above 40 degrees C, but something like this would do:
On Fri, 10 Oct 2008 09:59:05 +0100 someone who may be Adam Lipscombe wrote this:-
are fed from the
self-contained hot water and
it is the hot water
1) provide a hot water cylinder in the annexe to feed the hot taps there. No need for fancy mains pressure ones.
2) install controls in the annexe to control the heating and hot water in the annexe. A system with one pump and motorised valves or two pumps will be fine. You will have two hot water pipes going into the annexe, a flow and return, plus a cold water pipe. The flow and return pipes will be connected to your boiler in the most suitable way (which depends on the pipe layout in the main house and boiler room).
3) install a heat meter to measure the heat used in the annexe. Depending on your level of trust you may want this to be in a location you control the access to.
4) bill the occupants for the heat they use. Make sure that the tariff covers not just the oil but also a proportion of the maintenance of the boiler.
One model of heat meter is Part Number 17955 at , note that you also need to fit a flow meter.
All this work can be done by DIY.
All standard stuff, though in the UK many people are unaware of this approach. Presumably electricity in the annexe is on a separate meter already and perhaps water?
The tenants can then use as much heat as they want, and so can you.
The meter I posted a link to just measures the volume of hot water coming out the taps, nothing to do with the amount of energy actually used, so rather more rough and ready than David's approach. Personally I wouldn't go to great lengths to set a precisely accurate price, you just want to discourage constant deep baths, lengthy showers, and leaving the hot tap running for the hell of it. A bath is around 90 litres of water. I would have thought charging them 30p for a bath seems roughly reasonable, and enough to discourage constant rim- lappers. So say 0.3p per litre.
I would have thought that space heating is by far the greatest component of the energy they use, and where most of the scope for abuse lies. If you're going to make them use electric heaters for that that will largely solve your problem in itself. I can't be easy for two people to use hugely expensive quantities of hot water whatever they do.
I'm not suggesting this is a practical solution, but could a meter perhaps be added to measure the hot water flow into the annex - then simply charge for the hot water delivered?
I have read some (all?) of the other replies and was surprised that no-one seemed to have suggested a conventional hot water storage cylinder with an electric immersion heater. Simple and cost effective for you.
That depends on the configuration of the two properties. I take it that as an 'annex' this rented property is attached to the main house
- rather an obvious comment considering the heat source is currently shared!
But is there any reason why the header tank of the main house can't be used for the annex too ? I seem to remember that the OP said the main house is quite large which would imply that the header tank is quite high and quite possibly already supplies adequate pressure for the main house showers. Then it is just a local hw tank with immersion fed with quite an acceptable head.
A conventional hot water storage system needs a header tank which presumably doesn't exist. That's why a Megaflow was recommended by the OPs plumber. But I commented on this earlier - so you can't have read all the replies.
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