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Replacing a system boiler with a combi boiler

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Gemma

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First time using the forum so apologies if this isn't in the right place.

We're planning on fitting an en suite shower room in the space where we currently have built in wardrobes and a hot water tank. Just at the thinking stage at the moment. Since there is nowhere else to move the tank to, I am assuming replacing our (10 year old, vaillant ecotec) system boiler with a combi boiler is the obvious option? We haven't had any issues with the boiler, but we do run out of hot water if a few of us have a shower one after the other. We also have a spray kitchen tap that is supposedly suited to gravity fed systems but is very sluggish. I'm hoping a combi would fix both these issues..? (We shouldn't have a need to run 2 showers at the same time, the en suite is more to gain an extra toilet / someone use the shower while someone else is in the bath). Finally, we have a power shower over the bath at the moment, I know this will need to be replaced but I'd like to have the same powerful flow as we currently get, will this depend on what shower we get? On our mains pressure? Sorry if I sound a bit clueless!
 
Gemma Bamber said:
First time using the forum so apologies if this isn't in the right place.

We're planning on fitting an en suite shower room in the space where we currently have built in wardrobes and a hot water tank. Just at the thinking stage at the moment. Since there is nowhere else to move the tank to, I am assuming replacing our (10 year old, vaillant ecotec) system boiler with a combi boiler is the obvious option? We haven't had any issues with the boiler, but we do run out of hot water if a few of us have a shower one after the other. We also have a spray kitchen tap that is supposedly suited to gravity fed systems but is very sluggish. I'm hoping a combi would fix both these issues..? (We shouldn't have a need to run 2 showers at the same time, the en suite is more to gain an extra toilet / someone use the shower while someone else is in the bath). Finally, we have a power shower over the bath at the moment, I know this will need to be replaced but I'd like to have the same powerful flow as we currently get, will this depend on what shower we get? On our mains pressure? Sorry if I sound a bit clueless!
Click to expand...
At first sight I think it’s nuts to put a combi in place of a system set up. If you live on your own have no kids then maybe but even then no ....chking
 
A combi will not allow you to satisfactorily run two outlets. You say it’s not an issue at present but things change and it seems pointless putting in an en suite if you can’t use both showers simultaneously. You might as well just install a new loo
 
Thank you - you make a good point. Are there any other solutions I might not have thought of? No experience of electric showers but not heard good things. Space allowing we'd just get a bigger tank (or a megaflow?) but there just isn't anywhere else to site it.
 
You can yes but they’ll only produce xx amount lpm which would then be split between two outlets. The op was talking about having a nice powerful shower
 
Assuming we can put it in the loft, a bigger cylinder should help solve the 'running out of hot water' issue we have now? We get about 15 minutes of shower time at the moment and there's 4 of us so could do with it lasting longer. I did the calculations a while back and for the size cylinder we have 15 mins seemed about right.
 
Don't forget you can set the programmer to supply heat to the cylinder during the period your family normally takes showers. A modern cylinder can transfer 20kW+, which is enough to supply one or two showers continuously. Some programmers have a 'one-hour boost' that can be used if the times are less predictable.

Also keep in mind that, If you have teenagers, a shower that runs cold after 10 minutes is an effective way of stopping the hot water bill bankrupting you.
 
dancinplumba said:
power is down to pressure , if flow 20lpm on hot should be adequate for two hot shower outlets , stick a 25lt exp/accumulator on cold feed
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I’m not disagreeing mate but it won’t be at 20lpm after a few years of scale or poor upkeep. Sorry I get what you’re saying but I’m just being pragmatic that if a cylinder is an option it would give a superior result and probably a vastly happier customer and end result.
 
Chuck said:
Don't forget you can set the programmer to supply heat to the cylinder during the period your family normally takes showers. A modern cylinder can transfer 20kW+, which is enough to supply one or two showers continuously. Some programmers have a 'one-hour boost' that can be used if the times are less predictable.

Also keep in mind that, If you have teenagers, a shower that runs cold after 10 minutes is an effective way of stopping the hot water bill bankrupting you.
Click to expand...

Fair point - two teenage girls...
 
Combi’s suck basically. No one would really want one except
When they need to save space
Have a small gaff with one bathroom
Choose an installer who won’t or can’t fit a system or conventional set up
Combis are also cheap.
They are and always will be a compromise
Ok some in here will disagree but that’s what I think.
Rob Foster aka centralheatking
 
Just one more addition to the UVC camp.

No matter what combi you have, ALL quote a flow rate based on a temp uplift of 35 degrees. That means with a shower needing to be 43 the flow rate immediately drops. Then for 6 months of the year water temp entering the prop drops so its even less.

Combis are sh1te for showers unless stupidly oversized but then it causes prob by cycling on htg...
 

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