ADVICE NEEDED: Combi boiler Vs tank / Mega flow

[Jasmina]

I'm buying a house that has an ancient boiler (downstairs) and tank (first floor). There is a rubbish electric shower in the bathroom. Water seems to warm up ok in the rest of the house..

As I'm selling a flat and moving into a house I'm not sure what would be best. In my flat I have installed a Worcestor Bosch combi and it's fabulous! I lurve my power shower.

What is best in a house? Only one bathroom, but extra toilet downstairs. I do not want to lose pressure when in the shower when someone flushes the toilet downstairs or decides to do the washing up.

Replace the old boiler with a combi and free up space in a fitted cupboard upstairs where the tank is located. Or move tank to the loft as thats a better thing to do in a house? I've also read threads that talk about mega flow... but they seem to be for houses larger than what I'll be buying.

Any advice would be gratefully received.

Thanks in advance.

[Dulwich Born And Bred]

I am in a three bedroomed house and I have a combi boiler .

There isn't an issue at all with using the toilets ( I have two ) and the kitchen tap water .

The only issue is that I can't run the bath and then use the basin water in that bathroom to brush my teeth as if I use the hot water then there is no pressure from the basin hot tap water and likewise if the cold water is in use for but that is absolutely minor.

[Jeremy]

I'd just go for a combi... we have one in a four bed/two bath house with no problems. The installer should be able to recommend one with adequate output for the size of the property. Thermostatic shower valves also help to reduce problems when more than one tap is being used.

[Alex K]

No advice, only anecdotage. -- The tank in the loft came out, so did the hot-water reservoir in the airing cupboard; and into the airing cupboard on the landing, where the h-w r had been, went a clothes-washing machine, over a drain emptying into the piping system underneath the adjacent bathroom. That gave us space in the kitchen to install a dishwashing machine. No problems whatsoever with water pressure or hot- / cold-water flow. COMBI BOILER FOR THE WIN.

[HunterHtingSolutions]

Hi Jasmina,

I am an ex British Gas Engineer who has recently ventured out on my own, I have an unvented system (megaflo) in my house (which i have sited in the loft with my boiler) purely because I don't like the one tap operation of a combi system.

How many of you are living in your house? If there is only a couple of you then you may get by, but if you have children then it could get somewhat annoying! If you are having a shower and someone opens a tap or uses the washing machine it will affect the flow rate of your shower and will also fluctuate hot and cold.

The size of a combi will not give you stronger water pressure......If you have for instance 10 Litres a minute water flow coming into the property, a 28KW combi is capable of heating this sufficiently. Where as if you have 13-20 litres a minute coming in then a bigger boiler will allow more water to be heated instantly giving you a better flow of hot water.

The better the water pressure coming into the property, the less your shower will be affected if someone does open a tap (If you have a bigger output boiler installed)

Bottom line is Unvented Systems are the best Hot Water Systems you can get, PROVIDED they are done properly...Many are not! The problem with combination boilers are when they go wrong you have no CH or HW where as if you have an Unvented System you have the option of having an immersion heater as an emergency HW backup if the boiler goes wrong. You will ideally need a minimum of 20 litres a minute water flow coming into the property. There are options to improve your incoming pressure if it is not good enough. You can also get solar compatible cylinders.

The Unvented gets my vote but it does come at an extra cost...

If you have any questions or need any more advice please don't hesitate to contact Billy on 07986296453.

[Fuschia]

In previous small house and flat I always had combined boilers. There were occasions where another inhabitant turned on a tap while I was in the shower, affecting the pressure and temperature. We have now moved to a much bigger house with 3 showers and a large household. We have a megaflow, and it works brilliantly. But I believe they are very expensive.

I think you need a survey of the house and the existing plumbing and advice on designing the best system.

[JohnL]

Showers limit the flow of hot water I think to stop any chance of burning if someone turns on a cold water tap.

But I think my mixer needs cleaning out - luke warm - which is an issue

[Jasmina]

Hi everyone,

Thanks for all your replies - they are extremely helpful.

Only 2 in my household (including me), although we'll have guests staying some weekends.

HunterHtingSolutions - How am I supposed to find out how many litres per minute is flowing in to the property? Is this something a plumber could work out?

[ed_pete]

Your kitchen cold tap is more than likely directly connected to the mains and not fed from a tank. So it's just a case of putting a bucket under the tap and turning it on for 1 minute and then seeing how much water you've got.

[Jasmina]

Thanks ed-pete. So obvious and simple :-)

[HunterHtingSolutions]

Yes the bucket idea works but if you have very good pressure that bucket will fill that bucket pretty quickly! Yes we can measure exactly using a pressure testing kit.

[Jasmina]

Fair point, HunterHtingSolutions :-)