Replacement DHWC - Gledhill High Recovery?

[Schmill]

Hi all,

Just after some advice here, to make sure I am about to embark down the correct path

The 'complaint' is that the power shower in the bathroom runs 'less than hot' quite quickly after it is first used, and each subsequent shower after that is cooler still, until finally it's positive frigid!
This is whilst we all shower switching the shower on, getting wet, switching it off, washing, switching it on to rinse off, switching it off, wash hair, switch it on....
This was NOT how I had invisaged having a nice power shower would be - lol
With the winter now fast approaching (or is it here already?!) the effect is even more noticable, and I can only assume that it is due to the fact that the water stored in the tank in the loft will be that much colder when it enters the DHWC than it is in the summer.

The system is a pumped primary, gravity secondary, with the exclusion of the shower which has an external power-pump.
The water all comes from the cold water storage tank in the loft, with the hot water being heated by an indirect open-vented cylinder.
When the water is being heated the pipe entering the cylinder is very hot, unbearable to touch, which is what I would expect, but so is the pipe that leaves the cylinder.
I am currently presuming this to mean that the coil inside the tank is probably quite scaled, and therefore isn't transferring the heat into the tank very well at all?
The primary return to the boiler (a British Gas / Ideal RD2) is actually still so hot that the boiler thermostat will switch off the boiler with the system just pumping the hot primary water round and round, whilst the tank slooowly heats up.
This annoys me because the tank seems to take a long time to recover, there never seems to be 'enough' hot water, and I feel like I must be burning money with the coil not efficiently heating the water.

IF (and it's a big IF) all of the above is correct, I'm thinking the best course of action is a replacement cylinder. I currently have an 'unknown make', but it is a 450mm x 900mm 117L indirect cylinder.
MORE hot water would seem to make sense, but we are also keen to keep a functioning airing cupboard, so don't want to go TOO large with the tank. Due to this I started looking at the fast recovery cylinders, with my thoughts being that so long as the cylinder could recover quickly, there was a good chance it would also be able to maintain a decent level of hot water for a longer period too.

The one I am currently considering is the Gledhill High Recovery cylinder (previously called CondenCyl) such as THIS
I was thinking that the 1050x450 size would be best as this would give 140L capactiy, compared to the current 117L, AND would be a high recovery.

What are peoples thoughts on this?
Are the high recovery cylinders worth the extra money? (Do they recover that much faster than a standard part L cylinder?)
Gledhill seems to be a fairly 'major' manufacturer of cylinders, but what are peoples experiences with them?

Any other advice, recommendations, or pointers that you feel would be useful?

Thanks in advance!

Below is an image of the airing cupboard with the existing cylinder in it, in case there is anything visible that might be relevant, (the shelf above the cylinder can be raised to accomodate the 1050 cylinder, but we don't want to go too high with it if we can help it as the airing cupboard is used to store spare bedding & towels etc)

Untitled

• Schmill
• 20 Nov 2012
• 1

Untitled

• Schmill
• 20 Nov 2012
• 2

 

[PetePlumb]

Every cylinder change I get, I stick a Gledhill in. I like them, and they work well. Never had any problems with them. All connections are factory made with just a nut and olive to tighten up.. lovely.

 

[hazetimesfive]

i fit rm aquastel stainless, becoz they are cheap and tuff

 

[Agile]

You dont say anything about your boiler or system!

Whilst a high recovery cyl will always work, to get the maximum benefit you need a boiler capable of providing the power to the cyl.

Its unlikely you need a fast recovery though if you have managed with that old cylinder.

140 li is about right for two people. You dont say how many you have!

Tony

 

[Schmill]

You dont say anything about your boiler or system!

Whilst a high recovery cyl will always work, to get the maximum benefit you need a boiler capable of providing the power to the cyl.

Its unlikely you need a fast recovery though if you have managed with that old cylinder.

140 li is about right for two people. You dont say how many you have!

Tony

Hi Tony,

I did say about the system, but I'll give you it was buried in amongst the other information.

Boiler: British Gas / Ideal RD2
System: Indirect Open Vented, S Plan.

It is a 4 bed house, with 4 of us living there, 2 adults and 2 children, but we should consider it being 4 adults as we don't intend to move house in teh foreseeable future! (ironically the children take the longest in the shower, but that's by-the-by!).

Someone, somewhere, a long time ago, had given a formula to work out how much stored hot water you should have, but the result it gave was a rediculously large sized tank for what I would consider to be a 'normal' sized household.

Not wanting to take up an entire room with a hot water tank, (and still keep a usable airing cupboard) is why I decided to look at tanks that were somewhat bigger than we currently have (+20%), but also higher recovery than the (presumably) scaled, 'standard' cylinder that we have.

For instance, the example that they give on the site that I linked to was that a 120L 'standard' cylinder can be reduced to a 75L 'High recovery' cylinder.
Now I am not sure if that size relationship is linear through the sizes, but if it was it would imply that a 140L 'high recovery' cylinder would be the equivalent of a 224L 'standard' part L cylinder.

 

[arbitrary]

Am in a similar position/dilemma - what did you decide in the end?

 

[mickyg]

Fit a stainless steel high recovery cylinder, rewire the system to priority hot water, remove or leave balancing valve fully open. Get the boiler serviced and ask the engineer to make sure it is set on its max output.

 

[misterdubya]

They have an essex flange built in.

 

[Schmill]

For some reason I have JUST received the email to say that this post has replies?!

Anyway...

Phelix: Unfortunately finances took a bit of a dive not long after my post and as such we never replaced the cylinder... yet. On the bright side it does mean that I am still open to suggestions

MickyG: "Rewire the system to priority hot water" - What do you mean by this? The system currently has 2 motorised valves, one for rads, one for hot water, and what I presume to be a manual balancing valve on the outflow from the coil of the DHWC.
The boiler IS set to its maximum output, and from what I can tell there are no issues with the heat coming from that, its just getting that heat into the hot-water that is the issue

MisterDubya: So you can draw the shower water directly from them? No need to fit any other flange? - Excellent

 

[MeldrewsMate]

The cylinder may be, as you indicated, full of scale; so much so that there is little space for hot water!

Are you competant to remove the immersion heater and inspect the inside of the cylinder for scale?
The cylinder appears very old, and I believe you live in a hard water area.

If a large amount of scale is seen are you competant to remove the cylinder? If so you have two choices.
1. Replace with new, typical cost £230 for 1050x450 size + pipework mods.
2. Take existing cyl outside and tip it up, empty out the loose scale...the more there is, the better the result when you remove it! Cost is nothing but your time and some top-up inhibitor.

Once back in and refilled set both heating & HW to ON, and adjust outgoing gate valve so that there is about 10C temp difference between in and out; do this before the water reaches anywhere near usable temperature.

 

[MeldrewsMate]

If you go for a new cylinder you either need a 1" female boss at the top so you can re-use your Surrey flange, or one with a side tapping to feed your shower pump.