The quest for a powerful shower...
- Thread starter larpo
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Big I'm afraid ,although the footprint is the same as the smaller models (same diameter I mean, so it would fit into most airing cupboards.) the height is a lot more, about six foot seven I think.
If your combi is ten years old it is getting close to a typical lifespan of 10-12 yrs.
An unvented cylinder will use the same water supply as the combi, so you will merely have the two units fighting each other for a share of the incoming water supply.
A decent combi, such as the Vaillant ecoTEC 831 will give out over 12 litres of water per min. Typically you have to mix 3 litres of cold in with this at the point of use.
That gives 15 litres in total.
Most showers use circa 10 litres of water per min, unless you fit a drench head, in which case the manufacturer should supply a spec.
I cannot see any point in fitting an unvented just for showering, unless you have a 20litre per min multi jet 'flash as a rat with a gold tooth' shower. You will still have an old boiler which will need replacing soon, and if you have a standard shower you will see no benefit over an 831 whatsoever.
Finally, you should find out the flow rate into the property. If it is under 20litres per minute an unvented will be a waste of cash and floorspace.
An unvented cylinder will use the same water supply as the combi, so you will merely have the two units fighting each other for a share of the incoming water supply.
A decent combi, such as the Vaillant ecoTEC 831 will give out over 12 litres of water per min. Typically you have to mix 3 litres of cold in with this at the point of use.
That gives 15 litres in total.
Most showers use circa 10 litres of water per min, unless you fit a drench head, in which case the manufacturer should supply a spec.
I cannot see any point in fitting an unvented just for showering, unless you have a 20litre per min multi jet 'flash as a rat with a gold tooth' shower. You will still have an old boiler which will need replacing soon, and if you have a standard shower you will see no benefit over an 831 whatsoever.
Finally, you should find out the flow rate into the property. If it is under 20litres per minute an unvented will be a waste of cash and floorspace.
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The flow rate into the property is very high. We do want to use a big rainfall shower head. Not sure what these need in terms of l/min. Point taken about the boiler.
My brief search shows the Vaillant ecoTEC 831 at around £8-900. when you add the labour into the mix it seems this is going to push the cost well over the £1000-all-in that I have been quoted to fit the unvented system.
Any thoughts?
My brief search shows the Vaillant ecoTEC 831 at around £8-900. when you add the labour into the mix it seems this is going to push the cost well over the £1000-all-in that I have been quoted to fit the unvented system.
Any thoughts?
If your water pressure into the property is high, then one of these new fangled high HW flow rate condensing combis should provide a shower that can blast your wig off fairly effectively.
I have a Trevi Therm shower the other side of the wall from my Vokera Linea 28 combi, and after five years its still pretty good. Not quite in power shower country, but overall its brilliant! You've just got to make sure that plate to plate heat exchanger doesn't get full of gunk as that will knacker it.
The HW feed to the shower should be the first off the combi, and the take off as close as is reasonably possible to the combi. Your shower should be thermostatically controlled to avoid death by scalding.
I think your old combi is a bit like an old computer with not enough RAM,and possibly a scaled up plate to plate heat exchanger as well
I don't have much to do with unvented, but it is spoken of highly, so is certainly a viable alternative and will probably give a better shower..Not quite sure how the cost/economics balance out.
Have fun
Alfredo
I have a Trevi Therm shower the other side of the wall from my Vokera Linea 28 combi, and after five years its still pretty good. Not quite in power shower country, but overall its brilliant! You've just got to make sure that plate to plate heat exchanger doesn't get full of gunk as that will knacker it.
The HW feed to the shower should be the first off the combi, and the take off as close as is reasonably possible to the combi. Your shower should be thermostatically controlled to avoid death by scalding.
I think your old combi is a bit like an old computer with not enough RAM,and possibly a scaled up plate to plate heat exchanger as well
I don't have much to do with unvented, but it is spoken of highly, so is certainly a viable alternative and will probably give a better shower..Not quite sure how the cost/economics balance out.
Have fun
Alfredo
If your boiler is already 10 years old in two years you may have bought and installed an unvented AND a new combi. Or you may have bought an unvented and £600 of repairs on an old heap.
I was just trying to save you some money, assuming you first check out the incoming flow rate and the shower head water flow requirements.
I was just trying to save you some money, assuming you first check out the incoming flow rate and the shower head water flow requirements.
The poster has said that he wants a very powerful shower, and that he has good incoming mains pressure and high flow rate. In these circumstances there isnt a combi made that will get near an unvented cylinder, or a thermal store. Obviously it would be a more expensive way to go than just replacing the combi, but you would need a massive (very expensive) combi to give anywhere near the hot water this poster says he wants, and have you seen how much gas they use on full rate, ie when supplying hot water. Typically about 3.7 m3hr. I think that his plumber gave him good advice.
Gentlemen (and ladies, if there are any present) I'm impressed by the quality of the advice and debate on this forum. top marks.
The unvented cyclinder is now bought and payed for and will be installed this week. with any luck I will be mercilessly flayed by my new shower as of next week.
cheers!
The unvented cyclinder is now bought and payed for and will be installed this week. with any luck I will be mercilessly flayed by my new shower as of next week.
cheers!
W
Water Systems
larpo said:
Check your mains pressure and flow. If it is poor an unv etd cylinder will not solve the problem. If the combi is naff and water mains is fine then another combi will do the job. There are some good wall mounted high flow models around. Alpha CD50 will fill the bath as fast as a cylinder. The Baxi 133HE plus is about 16 litres/min and will give a good shower - you can have TRVs on all rads and electric wall thermostat with this model.
The highest flowrate Glow Worm combi is good as is the highest 40kW Worcester-Bosch.
The above are all wall mounted. Floor mounted combis deliver far higher flow rates, with some doing 3 bathrooms.
When people spout old wives tales about all combis filling a bath in half an hour don't believe it.
W
Water Systems
sooey said:
The Baxi 133HE plus is approx £900. That is not as lot of money. Far cheaper than a boiler and megaflo cylinder which takes up valuable space in his flat.
As the meter can take 6 m3hr it is well within range. The plumber was an idiot, that is clear.
Your confusing the issue now water systems, the poster has already stated that he has good pressure and flow rate and that he wants the most powerful shower he can get. He has also said that he has a 24 kw combi that needs a service, so it seems he has settled for an unvented cylinder heated from the combi he already has, as you know stored hot water supplied at a good mains pressure and flow will beat a combi any time. As for the meter handling 6m3 of gas, the point I was trying to make was that someones got to pay for all that gas (the poster)and a combi is working hardest when supplying hot water instantaneously , I don't think his plumber was an idiot at all, and I think if you read the first post on this topic properly you will agree.
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Personally I have fitted only the one 133He for a customer and have regretted that day ever since, yes the boiler produced 16litres of water through the hot tap but it never got hotter than tepid, Heat team have been out and replaced everything on the boiler still only 16litres of tepid water. only way to solve the problem was to fit pressure reducing valve on the outlet of the hot and adjust the hot down to a flow of 13litres. Never again will i fit a 133 over an unvented.
Lee
Lee
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