Combi for a 4 bathroom house

[timmyjane]

Opinion seems to be if you have more than two showers dont install a combi boiler system.

Problem. I want to convert my loft, huge water tank in the way. I want to put stairs up to the loft where a current hot water tank sits. I want 4 showers. Wish to let loft and one other guest room, so vital showers work properly. Good water pressure to the house but not tested, comes out so forcefully that the stop tap needed turning down a lot.

Currently have two showers and can only use one at a time without someone shreiking showers gone cold, so conventional system not working in my house, given we have good mains water pressure looked at combi systems.

The best combi system I have seen that seems to be able to give a flow rate of 45 litres a minute @ 60C is the ACV Heatmaster 85tc. As its a combined hot water tank combi boiler being fed off the mains, it could go in a downstairs cupboard, unlike gravity fed system. on the presumption I have good mains pressure I'm interested as it seems to tick all the boxes.

Anyone have this system in a similar set up, or knows how much it is.

Are there any alternatives more widely available (worried about servicing), looked at Glow worm ultra power 100/170 sx, has a good flow rate of 36 litres a minute but at 35C, is there anything else out there, think the ACV may be very costly.

Advice very appreciated.

 

[Dan Robinson]

They're not really combis. Just unvented cylinders with boilers bolted on.

Veissmann do the 222. Otherwise a separate boiler and unvented cylinder is best.

You could have a standard 30kw combi AND an unvented cylinder wired as a traditional s plan and get away with a smaller cylinder by feeding the kitchen and a single shower through the combi.


Thermostatic showers are essential in high occupancy households imho.

 

[timmyjane]

They all seem to be selling themselves as combi's with hot water storage cylinder. So as hot water from tank depletes the combi kicks in I assume and continues to heat cold water coming in from mains, dont know how different this is from conventional system I have, but any method that allows me to get rid of huge water store in loft and have more than 2 showers running is good, dont mind how achieved. There will be 6 in household if things go to plan, so volume of water usage likely to be high.

Have just looked at the Veissmann, (thanks) but flow rate was at about 20 litres a minute (whereas AVC is over 40), but cost I am guessing far less.

Your suggestion of 30kw combi feeding kitchen and single shower and an unvented cylinder, would the unvented cylinder need an additional boiler of its own (if so) could all this be placed in a 800 cm footprint up to 2.3 meters high (size of my cupboard) at ground floor level. Re routing pipework aside (as would have to do this whatever system I choose). Any idea of the ballpark cost of your latter suggestion parts only.

Thermostatic showers: - will I be an imho if just two large rooms let, will still be my family home. I'll look into thanks.

Would the AVC unit be adequate as a standalone for what I have in mind if the difference in cost between the two is small.

Thanks for advice.

 

[Dan Robinson]

The ability to run two showers at the same time is down to your incoming water supply.

You need this measured and tested by someone who knows what they are doing.

My combi and and unvented cylinder combination means only one boiler but gives you two independent heat sources.

 

[OwainDIYer]

My combi and and unvented cylinder combination means only one boiler but gives you two independent heat sources.

It doesn't really give independent heat sources. If the combi hot water is in use for extended periods the cylinder won't get reheated.

However having a cylinder somewhere does allow an electric immersion heater as backup. Lodgers (good ones) get very unhappy if no hot water.

 

[Dan Robinson]

It doesn't really give independent heat sources.

However having a cylinder somewhere does allow an electric immersion heater as backup.

 

[Agile]

I am worried for you because you seem to be blindly reading headline figures without understanding what they mean!

Hopefully you will have a qualified person installing them but be aware many are so short of work they will fit whatever you tell them to do.

In any case many do not know what these water heaters really do in any case.

I predict that you will be unhappy with anything that you select !

Tony

 

[ALEC1]

So as hot water from tank depletes the combi kicks in I assume

wrong assumption.

the minute you start drawing hot water the combi kicks in

at a low flow rate the hot water comes from the plate only
and at a higher flow rate from the plate and the store.

works very well.. I have heard from one of my clients of a 19kw 222 in a house with two showers, showering 12 people consecutively with no issues..

 

[dcawkwell]

Idea situation for a glow worm ultra power.
A cross between combi and unvented cylinder all in the nice once box.
Will outperform a 300 litre unvented cylinder and has immersion for back should it fail.

 

[timmyjane]

The ability to run two showers at the same time is down to your incoming water supply.

You need this measured and tested by someone who knows what they are doing.

My combi and and unvented cylinder combination means only one boiler but gives you two independent heat sources.

Thanks - Getting flows and pressure done on Tuesday. Have been looking into a number of solutions to problem, unvented seems to be quoted often so am researching.

 

[timmyjane]

I am worried for you because you seem to be blindly reading headline figures without understanding what they mean!

Hopefully you will have a qualified person installing them but be aware many are so short of work they will fit whatever you tell them to do.

In any case many do not know what these water heaters really do in any case.

I predict that you will be unhappy with anything that you select !

Tony

Hopefully by posting problem on forums like this, and taking on board advice suggested, getting water checks done, spending hrs reading technical info on boilers I am researching. Along with arranging already someone trusted coming round on Tuesday to discuss options (he couldnt fit me in for 3 weeks and has worked on my install of fire and flue, toilet install and rapid boiler system repair over past few years, along with specialising in fire and boiler installations) I hope I am doing a little more than just reading headline news to inform myself and not just accepting an inadequate unresearched system i kinda like.

 

[Dan Robinson]

Thing to remember is OP - no one likes a smart a7se, and a homeowner that has been furiously googling will only be partially informed, but will often think they know all they need to know.

Can very easily get the visiting engineer's back up.

However, it is refreshing to have a customer that appreciates the scale of the work required, without them automatically assuming the engineer is trying to make work.

If you catch my drift .

 

[timmyjane]

Thing to remember is OP - no one likes a smart a7se, and a homeowner that has been furiously googling will only be partially informed, but will often think they know all they need to know.

Can very easily get the visiting engineer's back up.

However, it is refreshing to have a customer that appreciates the scale of the work required, without them automatically assuming the engineer is trying to make work.

If you catch my drift .

Thanks, I'll bear your comments in mind. 20 years in finance and I still get newbies who think they know better, kinda why I hope I'm not the same.