Flowmax 180 combination

[darren6645]

I have a 180l flowmax thermal store on my first floor, water heated by my boiler on the ground floor and returned to storage where it is also used to heat radiators when required and provide mains pressure hot water via an internal coil and blender valve, open vented system.
I've read lots of posts and I'm now confused is my system classed as direct or indirect?
I've attached an image of my exact set up, no other f&e tanks or header tanks anywhere.
Thanks.

 

[ianmcd]

it is a
180 Litre - Range Flowmax Copper Direct Vented Thermal Store Combination Unit

The F&E tank is the little tank on top of the unit, why do you ask

 

[darren6645]

Yeah I understand the f&e is on top was just putting as much detail into post as possible.
Reason for asking is I've been advised to flush my system with sentinel x400 and it says on bottle can be used on all indirect systems.
Wasn't sure if that meant you couldn't use it on direct systems?

 

[ianmcd]

yes you can use it on your system, the word direct is confusing in that context, traditionally a direct HW system was something completely different, why have you been advised to flush the system ? what problems are you having ?

 

[ianmcd]

The most common problem with Thermal stores is the dosing of cleanser and inhibitor is, the sentinel 1L of cleanser or inhibitor will treat approx 100L of system water or on average 10 rads, you have 180L in your store before you start even considering the rads, so depending on the number of rads you have you will definately need to use 2 bottles of each and possibly 3, too many people dont use the correct amount as the cost soon adds up to do it correctly

 

[darren6645]

I was getting a noise when the boiler was on full flame, initial start up until water temp reached or if high demand, shower running heating on. It sounded worse if I slowed the circulation pump down and slightly better when I turned it up, sounded like a rumbling but only when on full flame.
The engineer that came out under my insurance policy said I had sludge and needed a power flush,didn't do any tests just assuming, so basically they wouldn't do anything. I need to fit a new magnetic filter so while the system is drained I decided I would dose it as don't fancy a power flush due to cost and micro bore. I don't actually have any other heating issues, water and radiators all red hot?
I've since turned the water temp setting down on the boiler and the noise has gone, currently set at 66c no noise?

 

[ianmcd]

which boiler do you have ?

 

[darren6645]

The most common problem with Thermal stores is the dosing of cleanser and inhibitor is, the sentinel 1L of cleanser or inhibitor will treat approx 100L of system water or on average 10 rads, you have 180L in your store before you start even considering the rads, so depending on the number of rads you have you will definately need to use 2 bottles of each and possibly 3, too many people dont use the correct amount as the cost soon adds up to do it correctly

Thanks for that I had read that somewhere else. I've got 2 to put in, I will then put 2 inhibitor in again when drained and flushed, I have always dosed with 2 inhibitors perviously, good advice.

 

[darren6645]

which boiler do you have ?

Vaillant eco tec plus 418, 7 years old in March has been serviced annually.

 

[ianmcd]

Vaillant eco tec plus 418, 7 years old in March has been serviced annually.

powerfush is definately not the answer, these boilers need to be set up properly, I have tagged @ScottishGasMan for you, he works for Vaillant and he will see I have tagged him he will be able to help you out, as a rule of thumb a thermal store boiler should be left on max at the thermostat, indeed some boilers didnt have a thermostat so that it couldnt be adjusted , the flow to your store from the boiler is huge and wont be blocked

 

[ianmcd]

I have a feeling that you need to turn the max KW rating down rather than the temp but will leave it to the expert

 

[darren6645]

ianmcd thanks for that, I totally agree with what you're saying, not that I'm any sort of expert my bit of knowledge is just through research and help from people like you.
I need to replace the magnetic filter anyway so thought it may be good opportunity to put the cleaner through, I've never had a cleaner through and I've been in the house 19 years this year.
Hopefully your friend can shed some light on the noise issue.
Thanks again.

 

[ScottishGasMan]

If its been working fine for years and the heat exchanger is making noise at a high temp then it may well be starting to choke slightly, doesnt take much on these to start off noise issues. (can also be a slow pump) unfortunately theres no absolute method to identifying what one is the issue (without expensive trial and error parts replacement) However chances are its probably a mixture of both.

Thermal stores (sludge buckets as their know) are fantastic bits of kit, except for the fact they essentially store loads of system debris and distribute it around the system while being notoriously difficult to clean fully.

As said, powerflushing can only be done on the radiator circuit, not the store, and powerflushing wont be effective on microbore generally.

Its certainly worth running some cleaner through it.

If your going to use X400, 3 bottles minimum for your system (no point spending the money and doing half the job) Drain system, fit filter to the return pipe of the boiler, add in the 3 bottles and refill allowing at least 2 weeks of running for best results. Try not go too much longer as some of the material will start to fall out of suspension much after that.
Drain the system (including opening all the radiator bleed points to let air into every radiator so that the water will fully drain out them all)
Refill, start circulating and then empty again, Ideally in your system your going to need to repeat this 3 or 4 times to A. get as much crap out the store as you can, and B. Dilute any cleaning agent down enough to the point where its no longer going to mix with other chemicals and cause problems.

Then finally redose with 3 bottles of inhibitor.

You can during the 2 weeks clean the filter out as much as you like, what filter are you going for?

I've had quite a bit of success on reducing and stopping noise issues with cleanser on stainless coil heatexchangers like yours, but if it doesnt work it would be a new heat exchanger (pricey and another 3 bottles of inhibitor again most likley)


FYI, your system is indirect. Direct and InDirect reffer to how the Hot Water is heated, although your thermal store is directly heated with circulating boiler water, the Hot Water for the taps is InDirectly heated via a coil in the store so its ok to use chemicals.


(Disclaimer - the above is not the best way to flush the system, but its the most viable for a DIY attempt)

 

[ScottishGasMan]

I have a feeling that you need to turn the max KW rating down rather than the temp but will leave it to the expert

In most other circumstances with a noisy 4 series you'd certainly be right, however heating a thermal store is like heating a massive LLH, so the water flow rate through the heat exchanger "should" be completely unimpeded, which is where a lot of noise issues on these boilers come from (typically 30/38kw versions fitted to restrictive circuits with small pumps) But an 18kw on a Store should not suffer from noise due to the output, it will likely be a slowing pump/debris collecting in the heat exchanger or probably mixture of both.

 

[darren6645]

Very informative cheers. I'll get another x400 tomorrow and put the 3 in for 2 weeks.
The filter I already have is a salus mag defender it's a replacement for the current one as the valve started to drip when I last cleaned it. It was still under warranty so they sent a new one.
I've had the water temp on the boiler set to 68c tonight and it's been quiet.