Unvented cylinders and solar panels

[MickDrury]

Hallo folks …

We are converting a house for hostel accommodation for up to 12 people and wanting to increase hot water capacity with installation of unvented cylinder(s) whilst also getting solar panels installed. Currently oil fired system which will remain.

I understand that up to 500 litres capacity needed …. we have 3 showers … if all wanted to shower in the morning. What’s the best arrangement for cylinders?

Not sure of size of solar panels but 3 panels each potentially heating up to 100 litres when conditions good. The solar installers have suggested 2 single loop cylinders, one as a pre-heat cylinder linked to solar and then this feeding 2nd cylinder heated by boiler. My concern is that it would seem the water in the solar cylinder would just be used once all the 2nd cylinder was drawn off … not very good use of solar panels. Could we have a draw off direct from solar cylinder thermostatically controlled?

I thought about a single large twin coiled cylinder … but expensive. What about two 250 litre twin coils linked in parallel both connected to solar and boiler? Would this work efficiently?

We need the system to work effectively … but at times there may be only 1 or 2 people staying there so we won’t want the full 500 litres hot. So it needs to be cost/energy effective too.

Tricky but any comments appreciated! Mick

 

[Agile]

Whilst you dont want to keep the water all hot thats what you will have to do!

Modern cylinders lose very little heat so its not actually a problem ( except in your mind! ).

In many ways what they are proposing is best but there are other ways to do it.

More important is to ensure your mains water supply can really give about 40 litres per minute to power three showers at the same time.

Tony

 

[Bambergaspipe]

We need the system to work effectively … but at times there may be only 1 or 2 people staying there so we won’t want the full 500 litres hot. So it needs to be cost/energy effective too.

Do`n`t get too excited about solar power heating your hot water, it won`t, it will help but the difference in temperature will still be made up by your conventional boiler, if you think solar will give you hot water at 56 degrees forget it.

 

[Agile]

The rule of thumb is 2-3 m² of panels for a family of two adults and two children.

Its probably not cost effective fiting more than about 5 m² of panels.

The problem with solar is that you get more heat then you can store on a few days in the year and only a smaller contribution towards water heating for most of the year.

Tony

 

[oilman]

if you think solar will give you hot water at 56 degrees forget it.

Unless you use one of these.

 

[Bambergaspipe]

The problem with solar is that you get more heat then you can store on a few days in the year and only a smaller contribution towards water heating for most of the year.

Problem with you mate is you don`t know what you are talking about

 

[Bambergaspipe]

[Unless you use one of these.

Which still won`t provide your hot water free at a temperature of at least 55 degrees.,Yeeeeeeeeeeeeeawwwwwwnnn.l

 

[oilman]

Nothing is "free" in the way of energy, but it will raise the temperature to well above 55 in the right conditions.

 

[oilman]

I didn't have to trawl the net, I have one fitted, I know what it does.

 

[ajstoneservices]

You should plumb them in using one as a pre-heat.
The cold feed into store 2, hot out into cold feed of store 1.

You will need a Resol BS Plus or Pro and a Honeywell V4044C 1288 22mm 3 Port Diverter Valve or similar two wire diverter valve.

The controller will load store 1 first then switch to store 2. You will need one twin coil for store 1to be heat by solar/boiler and a single solar coil for store 2.

I've not fitted a Willis but those that have say they work, I'm yet to be convinced as a PHE or side arm HE will do exactly the same at less than half the cost.

 

[AndyPRK]

I'm more worried that they want to take their shows in the morning
Can't they pop back at 3pm for their showers ?

I wonder how useful this will be for you.

You would need some east facing panels.

You may want to ask here :

http://www.navitron.org.uk/forum/index.php#3

 

[ajstoneservices]

I'm more worried that they want to take their shows in the morning
Can't they pop back at 3pm for their showers ?

I wonder how useful this will be for you.

You would need some east facing panels.

You may want to ask here :

http://www.navitron.org.uk/forum/index.php#3[/QUOTE]

Andy,
Why would he need some East facing collectors? is your thinking that they would contribute more to the system for early morning showers? if so, its wrong.

Also, the Navitron forum is not the best place to look for good solar thermal system information, just last week forum members advised someone to replace his Kloben 21 cpc collector with one of their 30 x 50mm collectors.
The Kloben a licensed copy of the German Ritter it is one of the very best performing collectors on the market, its output and build quality is far superior to the Navitron, in fact it has twice the output. The OP on their forum posted details which clearly showed he had system installation faults and not a collector fault.
The forum has only two contributors worth listening to, MickB and Lightfoot, the others have been sucked in by misguided loyalty to promote Navitron above all others, most have only ever installed one system, their own, some of the more vocal, not even that.
Their forum should be treated as a guide but refference should be made to others as much of the information given there is plainly wrong.

Their site gives output figures which they know are incorrect but claim to be unable to correct them and say its down to the web designers. You could end up as some have, buying less collector area than you actually need leaving you disappointed those that have voiced their disappointment have been vilified by one of the moderators and some forum members to the point that they leave the forum.

Their installation instruction contradict advice often given by the professional installers whose installations bare little resemblance to Navitron's guide. Today again someone has installed his system to their instruction only to find one of the directors contradicting it.

There is no doubt that Navitron is a good outfit but, they are no better than most of the suppliers out there, many offer superior products at better prices too.

 

[kevindgas]

OP the gain you will get varies from day to day but apart from the crappiest days you will get something
if the system is sized and installed correctly you can get cheaper hot water most of the year.
free - never
as you say the time you need the most water is in the morning this isn't a problem as you use the water heated the day before - topped up by the boiler
i have seen several installs like you describe and every landlord/hotelier i have met is happy with their system
use the solar to preheat and the boiler to top up in the morning
my own panel fitted on my old house was south facing (30 tube Apricus collector) it produced hot water without a boiler top up from may to oct (boiler wasn't even switched on) the cylinder was a 220 litre solar unvented cylinder fitted in the loft.
during the winter a 10 to 15 min top up in the morning produced enough hot water for daily use including an 8" rain water shower fitted in the bathroom

 

[oilman]

Why would he need some East facing collectors? is your thinking that they would contribute more to the system for early morning showers? if so, its wrong.

Of course it's not wrong, you may have noticed the sun rises somewhere towards the east.

 

[ajstoneservices]

Why would he need some East facing collectors? is your thinking that they would contribute more to the system for early morning showers? if so, its wrong.

Of course it's not wrong, you may have noticed the sun rises somewhere towards the east.

Utter rubbish, perhaps you'd like to explain how that will make a useful contribution. did the OP state anywhere he had an E/W roof? if he has 500l of stored water his cost will be significantly lower installing a south facing system and get no benefit at all from east facing collectors.


Sorry of course you're right the sun does rise in the east