What replacement heating system to go for and shower options

JLC9779

HI there, I wonder if you can help. We are presently in a detached house, with 4 bedrooms. There is a family bathroom with an electric shower over the bath. There is also an ensuite which has a shower run from the hot water tank in the airing cupboard. It is a conventional boiler with expansion tank and cold water tank in the loft. We moved in a couple of years ago and it is the original boiler which is working still and we replaced the fan a few months ago.
The reason why I am asking is that we are about to replace the bathroom and have the opportunity to replace the electric shower with something else or replace it with a new electric shower and just keep the system the same.
We realise we will probably have to replace the boiler with something more efficient at some point, and just wondering whether we should do it now before doing the bathroom to give us better options in the bathroom. There are only two of us living in the house for the majority of time and just friends and relatives stay occasionally.
We are quite happy with having the airing cupboard and don't need any space in the loft.
Just wondered what people would recommend in terms of heating system and also showers etc.

EssexExile

If you are happy with things as they are then I'd leave it as it is. I don't like electric showers so I'd go for a pumped shower from the hot water system, others would do it differently. As for the boiler, just get a new more efficient one to replace the old less efficient one when it finally packs up.

nofoollikeold

1. I think there is a lot to be said for sticking with a conventional boiler rather than a combi.  My preference is for a heat only boiler, with a sealed central heating system.  Reasons:
1a. They are less complicated than combi's so less likely to give trouble.
1b. Things like motorised valves, pumps, etc are external, so you can pick the best components and are not dependent on boiler manufacturer's replacement costs for these parts should they need replacement.  This applies to combi and system boilers.
1c. Because you are storing hot water, the boiler itself can have a smaller kW rating, which makes the initial purchase cheaper.
1d. A smaller boiler may (only MAY) avoid the need to install a bigger gas pipe from meter to boiler.
1e. You have the resilience of stored water in the event water is cut off for a period.  I live in London, and we lose the water supply three or four times a year, generally only for a few hours, but it is till a nuisance and its good to have stored hot and cold water.  
1f. You can have an immersion heater in the hot water cylinder, so you have an alternative source of hot water (not central heating) in the event of system malfunction.
2. There are disadvantages, including:
2a. The water pressure issue.  A combi gives you mains pressure hot and cold throughout the property (depending on how it is installed).  So you don't need shower pumps.  
2b. The loss of heat from stored hot water.  I think this is less of an issue than it used to be, as a good, well insulated, cylinder will lose somewhere between 1 and 2.5 kWh per day.  For water heated by gas this amounts to around 20p per day, perhaps 3 times that for electrically heated water.
2c. You still need space for the cold water storage cistern and hot water cylinder.  Provided you have a sealed heating system you won't need the small feed and expansion tank for the heating.  However, sounds as if you aren't too worried about the space.  
3. A shower run from the hot water system, rather than an electric shower, gives a much better shower in terms of flow.  However it needs a bit of pressure to get that flow.  If you have stored hot water there are two ways of achieving this:
3a. With a decent shower pump.  The better ones of these will comfortably handle two showers.  Pumps need to be plumbed in properly on their own hot and cold supplies from the hot cylinder and cold cistern, in accordance with their manufacturer's instructions.  My own favourite is Stuart Turner (Monsoon range), but some people prefer Salamander.  
3b. With an unvented hot water system.  This has a hot water storage cylinder, heated by the boiler (with immersion back up) and pressurised by the incoming mains.  You can get rid of the cold water storage system in the loft and have mains pressure hot and cold water at every outlet.  They are more expensive than conventional cylinders, must be fitted by properly registered (G3) engineers, and should be serviced annually.  You don't need pumps, but if the water mains are off, you have no backup water.
4. If you go the combi and / or unvented hot water cylinder route, you must have decent incoming water pressure and flow:
4a. Combi: 1.5 bar or more pressure, 15 litres/minute or better flow.
4b. Unvented: 1.5 bar or more pressure, 20 lpm or better flow.
5. If replacing the bathroom prior to deciding on the eventual system, I would suggest installing a mixer (non-electric) shower, but bring the pipes from the shower out separately from bath / basin / WC pipes to an accessible point.  If you decide to go pumped, then you can connect the pump to these pipes.  If you decide to go unvented, you can just connect them in to other hot / cold pipe work.

Jeepers_Creepers

Wow, nofoollike old! That's comprehensive :-)

There is no right or wrong answer, JLC - each person has to choose their own system depending on their own circumstances and preferences. 

Some pertinent factors, I think: it's mostly just you two, but you do have folks staying over now and then. And, the existing boiler is coming to the end of its life, so you are anticipating a replacement at some point in the nearish future?

Ooookkaaaay. First, I have to say I hate electric showers and couldn't personally live with one. I can't remember the last time I had a bath, so our shower has to be decent. We have a combi boiler (30kW) and this gives a great shower. Yes, it's only 'one shower at a time', but that has simply never been an issue for us (3 adults, 2 teenage kids) as we all know when someone is going for a shower. This might be an issue in some households should folk Q to have showers in the morning, but - really - how long does a morning shower take? 5-10 minutes? 

You have a conventional shower in the en-suite? How well does this work - how good is the flow? Could this be improved further in a 'passive' way by raising the CWS tank in the loft higher? What happens to the en-suite shower flow when someone turns on a hot and cold tap elsewhere? Ie - I wonder if the existing setup could cope with 2 conventional showers if they are thermostatic and designed for very low pressures - 0.1 bar upwards? If so, that's the cheapest and simplest answer - just replace the boiler for another conventional (or 'system') type, and keep the cylinder.

Other options have varying amounts of compromise to them. For example, a combi will cost more than a straight replacement (around twice as much), but will give one great shower at a time, and you can lose the hot cylinder. Changing to a pressurised (unvented) hot cylinder could potentially give you TONS of flow to more than one shower at a time, but will cost more than twice as much (ie new boiler + new unvented cylinder). Fitting pumps to your existing system is potentially a cheap option - £undreds for the pump, and a new boiler when it's needed - but then you'd have to cope with nasty gushy things. I hate them (but lots of folk think their great...)

You need to decide what YOU want, and then consider the cost of having this.