Thermal Store Installation

[bernardgreen]

Try and use some alternative thinking FFS.

Since any water stored in a tank should by ultra safe regulations be considered as less than potable quality then all potable water sources have to be direct from the mains and thus ( unless a pressure reducer is fitted ) all potable water will be at mains pressure. Or is there an alternative. Perhaps cold water storage tanks with UV anti bacteria lighting.

Water from water bowsers for emergency supplies has to be potable ( not harmful ) but need not be wholesome ( maybe adverse in taste and / or appearance )

 

[electrogear]

Standing losses were the biggest issue I found. Low head systems breed Sludge too.

You have to keep the thing hot all the time.

Unvented over vented is very much application dependant. But a dry loft and mains pressure potable water everywhere without the noise of pumps is the main advantage.

Do the standing losses make it less efficient than any other system? i.e. don't you get the same standing losses with an unvented system and a vented tank with CWS? If not then why do you get greater standing losses with a thermal store?

With the sludge (I presume you mean in the tank itself rather than the primary / secondary coils?) can you not just drain it and clean it every so often? Inhibitor, water softeners etc?

When you say it needs to be kept hot all the time, why is that? Can it not run off a programmer the same way a normal vented hot water tank does? I understand if there's a bigger volume you may need to heat it earlier before use, but what's the point in heating it for the 16+ hours of the day whist you're out the house or in bed?

 

[Dan Robinson]

Standing losses are higher. The rated heatloss in the blurb is universally twaddle - cylinder or TS.

With sludge - why have a system that needs more maintenance. It costs more - which was your reason for not having an unvented in the first place. You also need gallons instead of litres of inhibitor which needs replacing when drained/depleted.

You're heating a bigger volume so it takes longer to react and costs more - again standing losses.

Unvented cylinders can be sized more closely and because of the reduced volume of system water the reheat is quicker and can be shared with the heating at the same time. A TS needs to heat up before the heating works.


Like I said - unless you need to merge multiple heat sources, or have insurmountable issues with the safety discharge, then TS's are not worth the hassle and additional cost.

Trust us. We do this stuff for a living.

 

[electrogear]

Standing losses are higher. The rated heatloss in the blurb is universally twaddle - cylinder or TS.

With sludge - why have a system that needs more maintenance. It costs more - which was your reason for not having an unvented in the first place. You also need gallons instead of litres of inhibitor which needs replacing when drained/depleted.

You're heating a bigger volume so it takes longer to react and costs more - again standing losses.

Unvented cylinders can be sized more closely and because of the reduced volume of system water the reheat is quicker and can be shared with the heating at the same time. A TS needs to heat up before the heating works.


Like I said - unless you need to merge multiple heat sources, or have insurmountable issues with the safety discharge, then TS's are not worth the hassle and additional cost.

Trust us. We do this stuff for a living.

To be honest I don't know who to trust! The manufacturers have a vested interest (obviously!) I've had several conflicting opinions from plumbers on here and face to face and most installers are biased because of ease of installation/profit or other reasons rather than experience on what happens after the system is installed. My dad used to own a plumbers merchants and he think TS are a good idea but doesn't know enough to give me an informed opinion. You're obviously trying to send me down the unvented route, but then you've given me some sketchy answers (no offence) so I think I'll have to see if I can find some facts and figures so I can actually do a direct comparison.

I can do maintenance myself on a TS, but not on an unvented system because of the safety regs etc. I think perhaps you misunderstood me there.

I'll ask my plumber to quote me for both and mull it over...

 

[Dan Robinson]

Well there's not much more I can say.

I've had all three options. I have an unvented cylinder now and am sticking with it.

I do this for a living.

 

[bernardgreen]

I do this for a living.

A couple of years ago a friend needed to replace the ancient gas boiler. He got a few quotes. All but one suggested ripping out the tanks in the loft and the cylinder in the airing cupboard and going un-vented.

The one who suggested keeping the existing system and replacing only the boiler after a good flush of the sytem was a waged ( or salaried ) person working for a nationwide organisation. He would be paid the same amount per hour whether he was on site or waiting for the next job. No matter what system he installed his wages were the same. The others were all self employed and aiming to make the best profit from each and every installation they did.

This could be seen as examples of maximising profit being a major influence on the advice the self employed plumber offers to the client.

 

[Dan Robinson]

Well if it happened to your friend the it must be the same for every survey.

 

[Hugh Jaleak]

Those 'who do it for a living' are also faced with customers who, through use of the internet, think they know it all, or know better, customers who come to sites such as this and query every last detail, and also other contributors, (someone clogging up other threads right now for example, who also, through use of Google, (other search engines are available), think they know best....)

These people 'who do it for a living' also have families to support, and a reputation to uphold. With the use of social media it is as quick to get a bad reputation locally as easily as it is recommendations. Work often comes by word of mouth, and anyone who can 'come tomorrow' I have to question why they are not busy? Admittedly everyone has their preferences, but when regular contributors advise the same (or a similar) setup to that which they are using themselves then I would be looking seriously at that advice. Bear in mind most of us posting on here are giving up our time to help, and rarely, if ever, earn a penny from their contributions to this forum.

 

[Razor900]

Well there's not much more I can say.

I've had all three options. I have an unvented cylinder now and am sticking with it.

I do this for a living.

There is another option Dan!!

Why don't you try two combi 's

 

[shambolic]

Well there's not much more I can say.

I've had all three options. I have an unvented cylinder now and am sticking with it.

I do this for a living.

There is another option Dan!!

Why don't you try two combi 's

 

[shambolic]

I wouldn't touch a thermal store with a bargepole. Seen too many sludged up to feck. Wreck hex in boilers. 8litres of inhibitor required.
Also the corrosion and therefore sludge rate is multiplied by the constant store of 80deg.
In summer the room where store is is roasting.
Boiler on 24hrs a day to keep store warm. Have seen poorly fitted ones where boiler can't cope when heating on for a few hours as store cools down to much to provide hot water.
If you get a store it MUST be fitted perfectly to work.

 

[electrogear]

Well there's not much more I can say.

I've had all three options. I have an unvented cylinder now and am sticking with it.

I do this for a living.

Those 'who do it for a living' are also faced with customers who, through use of the internet, think they know it all, or know better, customers who come to sites such as this and query every last detail, and also other contributors, (someone clogging up other threads right now for example, who also, through use of Google, (other search engines are available), think they know best....)

These people 'who do it for a living' also have families to support, and a reputation to uphold. With the use of social media it is as quick to get a bad reputation locally as easily as it is recommendations. Work often comes by word of mouth, and anyone who can 'come tomorrow' I have to question why they are not busy? Admittedly everyone has their preferences, but when regular contributors advise the same (or a similar) setup to that which they are using themselves then I would be looking seriously at that advice. Bear in mind most of us posting on here are giving up our time to help, and rarely, if ever, earn a penny from their contributions to this forum.

I never said I know it all, all I've done is asked questions and asked for facts/reasoning rather than anecdotal evidence or "just trust us". I'm an engineer myself (instrumentation) so although I do use google for research, I have a good understanding of flow/pressure/temperature but I have no direct experience with domestic hot water systems, hence my questioning "every last detail" as you put it. It seems sensible to me (for safety reasons and practicality), to have a TS over a pressurised cylinder. Most of my work is around industrial safety instrumented systems (pressure/level/temperature measuring devices and their respective executive actions to shutoff valves, blowdown valves, ESD systems etc) and I know the expense that these systems bring with them, in terms of testing, initial cost, certification etc and I'm having a hard time at the moment understanding (quantatively) the differences in efficiency between TS and unvented that makes unvented the way to go but I'm also wondering if you can really have a reliable safety system that costs relatively little money, in domestic terms.

 

[Dan Robinson]

Part of the safety system on any domestic hot water application is taken care of with modern boilers.

The relative cost is absorbed across multiple components made by multiple companies and packaged by the OEM.

 

[Corgigrouch]

Well I love Thermal stores but for the life of me fail to understand why there is even a discussion about this... If all you want is mains pressure hot water and a link up to solar thermal then a twin coil Unvented is the only sane option... I fitted an unvented thermal store, linked to solar thermal for a chap a few months ago... He researched and supplied the product, I fitted...The only advantage that I can see is that he could have a little bit of heating when the solar panels are working....But then, why would you need heating whilst the sun shines?....He does have 3 pumps, a flow switch and a couple of relays to fail but he is cool with that.

The only sane use of a thermal store would be to link up a gas or oil boiler to an uncontrolled heat source....Only other time one would be fitted is when a customer with more teeth than brain cells is allowed to use Google

 

[electrogear]

I suppose the chance of all of the safety elements failing and leading to the boiler producing >100C water and the relief valves not opening and the thermal cutout not working is virtually nil, if the system is maintained on a yearly basis. I think I'm convinced, it's just I'm a bit stubborn. Apologies if I was rude to anyone, I didn't mean to be.

So when I size my cylinder, I guess I just need to calculate for 2 mixer showers and a hot tap running at the same time for say 20 mins (worst case scenario) how much volume I'll use and base the cylinder volume on that?