Central heating - Last minute advice

[Andeh13]

I have settled on a conventional Central heating system but before I put my money where my mouth is I have a few questions.

I have water pressure around the 10L/min mark, which have been told is the minimum for a combi boiler but will work. Nobody wants to tell me how much Kw I can get out of it though, with numbers between 20-30Kw given (not exactly confidence inspiring). I have a 7.5Kw ''power'' (HAH!) shower currently, which will need replacing at some point, so I am guessing the 25ish Kw central heating system will not give me a shower with 3-4 times the pressure as currently?

Any good brands to look for or avoid? The only thing the installers/quoters seem to agree on is mocking my weedy shower & telling me they can do the best price. With price varying from British gas with a ''you look stupid'' quote of £5800 to an independent guy with £3850.

I am looking at 6 radiators & a towel rail, combi boiler & current system (warm air) being taken out. Can anyone advise on what prices they quoted and what sort of setups they went for?

cheers guys

[GoNz0]

have you checked the valve in the street to make sure the valve it fully open along with the incoming one ?

http://www.worcester-bosch.co.uk/hom.../find-a-boiler

[Andeh13]

I will have a look tomorrow for it! I am at the top of a slight hill so wonder if that might play a part, it is still a fairly poor show tbh!


Thanks for the link, going to have a look for one that is one brand specific though! That being said, the name Worcester Bosch has some up a few times.


edit: My biggest concern is getting a decent shower, getting up before the sun rises is going to be fairly gut wrenching come winter so a good shower to wake me up is worth its weight in gold IMO. With a combi boiler (10L/water around 25Kw) can I expect a decent shower? Does anyone's system come close to my figures and who could comment? Thanks

[GoNz0]

well tbh my combi is restricted against mains pressure m8 and you still get a damn fine shower even with the cheap head i got with it, i have since swapped to a expensive head thats more restrictive and causes more of a jet. it wont be the same as a power shower, if you are going to get a standard boiler with hot water tank you need a power shower but a hell of a lot better than hot water tank, otherwise hook up a shower head to the tap and see what comes out.

the link i sent you to is just the WB brand as they are rated very high.

[peterb]

Not quite sure what you mean in the first post.

Firstly you have quoted flow rate - not pressure. Flow rate is a function of pressure and the pipe work. How pressure with a small bore pipe will give a low flow rate - but you could get a high flow rate with a large bore pipe at a low pressure.

Secondly the power output of the boiler is largely immaterial in terms of the shower, depending on the type of boiler you have.

If you really are going for a conventiional boiler, with an indirect hot water cylinder, then the shower will be fed by the hot water tank. A high output boiler will heat the water tank up quicker, but won't make any difference to the actual temperature of the shower. The pressure will be dictated by the height of the cold water tank above the shower head, and without a pump is unlikely to give the effect you desire.

If you are using a combination boiler where the domestic hot water (DHW) is fed at mains pressure, then you are unlikely to need a pump. I only have indirect knowledge of these systems, but the Worcester Bosch has a hot water reservoir in the boiler that is part of the heating system, and the DHW is heater by a coil in that reservoir that acts as a heat exchanger (the reverse really of an indirect hot watere cylinder, where the heat exchanger coi;l is part of the closed boiler loop)

Again in this case, the output of the boiler will be dictated by the central heating load. The temperature of the shower will depend on the flow rate, but these boilers seem to be very popular and effective. (but at the more expensive range of the market)

The other sort of combination boiler heats the water going through a heat exchanger heated by the boiler flame, but they are not usually multipoint and not recommended (AFAIK) for showers.

There are variants on the conventional system with pressurised heating loops and multipoint outlets - and indirectly heated mains pressure cylinders - but again the temperature will depend on the flow rate.

As with most things, you tend to get what you pay for. There are also a lot of cowboy plumbers out there so check who you are dealing with. Either go for someone who is personally recommended to you, or go for one of the big companies, lioke British gas, then at least you have ssome comebacjk if tyou don't get what you want - although you may pay more.

It might be worth while stating in writing what performance you want from the show - flow rate at a given temperature for example, although you may have difficulty in measuring that later to ensure that the system is in spec.

The big names in boilers are Vaillant, Worcester-Bosch, Potterton, Glow worm and one or two others. A Google search using the term gas boilers brings up a lot of info. It is a big investment, so do your research carefully. - then you will be in a better position to ask questions and to assess any quotes you might get.

A good place to start though

http://www.gasboilerguide.co.uk/

[GoNz0]

if you do go for a Worcester Bosch combi i suggest getting a decent controller to go with it that allows you to set eco mode while you dont need HW on demand, i upgraded mine to the controller that allows you to set 5 temps throughout the day 7 days a week and enable the pre heat (eco off) of the hot water for the morning shower and between 5-10pm when your going to need hot water fast! (also set on all day at weekends)

[oolon]

So feed the water from a tank and put a compressor on it, either feed the cold which would then be slowly replaced leaving the mains pressure for the hot or feed both. This would only be a problem if you needed constant hot water all day, so the tank would have no time to fill back up. I know with combi bollers people like to get rid of the tank however they do have there uses. You have a tank sized amount of water all you need to do is get it to the destination fast enough.