Water going hot-cold-hot-cold. Boiler? Worcester Greenstar 30si

Alex1983

The pressure issue i would think is unrelated to the hot water temperature issue, the pressure is the pressure inside the heating system and unless was down to next to nothing isn’t likely to cause your problem.

With out seeing your boiler fault it’s hard to say for sure but it sounds like you have to faults. I would get it serviced get the expansion vessel checked/ recharged as this will more then likely cure your pressure issue and they can check the plate heat exchanger, this is where I would think your hot water issue is from what you’ve described.

Pennywise

JustAnotherSaver wrote: »

Hmm interesting you mention that as earlier in the year they did the gas supply to all the houses in the area. They had to dig up a section down the side of our hose near the gas meter & i don't know what they did, installed new pipes or something (may not have been new pipes btw, i'm just guessing). A guy had to come out & look into the meter a couple times.

If it's the same has happened to us, they did our whole street, and put in some kind of liner in the existing pipework. At the time, the workmen said it was to avoid replacing all the pipework to everyone. When that was done, our boiler was unaffected as it wasn't a combi at that time - I believe combis need a higher mains pressure than the conventional. It was when we converted to a combi that the low pressure problem arose. Presumably, either the liner made the mains too narrow to support the high pressure needed, or there was some "kink" in the liner cutting the pressure. National Grid ended up digging up the pipe from our meter to the middle of the road to replace the whole length. Very simple pressure check at the meter - any competent GasSafe engineer can do it - that's why it was so annoying for us that our boiler installers didn't - literally a 2 minute job!

southcoastrgi

They will generally push a plastic pipe through the old pipe, normally this is 20mm & will service around 32kw in your home, if your gas appliances are more than this then the pipe will normally need to be replaced

JustAnotherSaver

Response from Worcester - it's no longer under warranty

[FONT=&quot]The boiler warranty has now expired,we have two payment options for a Worcester engineer to attend and repair your boiler.[/FONT]
[FONT=&quot]The first is a repair only charge of £275.00. This will cover your Worcester boiler and its Worcester controls for labour, VAT and most parts however, should the boiler require a significant part, (such as a shell, a tank or back plate) or if the boiler is beyond economical repair, then the engineer will quote a revised charge on the day. Any parts fitted will be guaranteed for a period of 12 months and payment for the appointment is reserved, by credit or debit card, at the time of booking and then debited after the appointment has been completed.[/FONT]
[FONT=&quot]The second option will cover the cost of this repair and will also provide a further 12 months breakdown protection at a cost of £300.00, which is payable via direct debit in 12 monthly instalments and administered for Worcester, by Domestic and General. [/FONT]
[FONT=&quot]The charge includes labour parts and VAT, however if we find that we are unable to repair the boiler, or that it is uneconomical to repair, then you will be given a full refund. Only your Worcester boiler and its Worcester controls are covered and full terms and conditions will be sent to you within 14 days of taking out the cover.[/FONT]

So would it be right to say that it's best to get a gas registered boiler repair guy in to take a look as he may be cheaper than Worcester dealing with it?

magn8p

I have exactly the same model installed by previous owners last year.

Not sure if it helps but the optimum pressure when the boiler is cold is 1.5 bar. Watch https://youtu.be/zUsBw1ZpiKY - a 5 min tutorial from Worcester about re-pressurising their boilers.

As part of this, you will have to turn the power for the boiler off which perhaps will also help you reset it.

Hope it helps.

JustAnotherSaver wrote: »

That'd help then i suppose :rotfl:So when i hit the yellow pages what am i actually looking for?


And wouldn't you know it. I stopped by my mothers for a shower tonight. My wife braved our shower ... not a problem.

Just had the tap running for a couple minutes - no problem at all. Only thing is the pressure is reading almost 2 bar. I know it'll rise but it seems to be all over the place. It was about 0.5-0.75 bar when my wife was having a shower. Settles around 1 bar. I don't know if all that behaviour is normal or what.

Turned the central heating on. Our room is 16c when we start. Turned it to get to 21c. The setting is auto but you can set it to temp manual. Anyway it got to 17c and then stopped. I don't know if that's more the settings than the boiler itself though.

magn8p

IMHO you are probably better off going for Worcester gas engineer to repair it for you. At least they know what they are doing unless you know a really trust worthy gas engineer who knows his stuff.

I am also keen on their second option. Gives you a peace of mind for 12 months and they seem to promise to return the charges if they can't fix it.

JustAnotherSaver wrote: »

Response from Worcester - it's no longer under warranty





So would it be right to say that it's best to get a gas registered boiler repair guy in to take a look as he may be cheaper than Worcester dealing with it?

HUMBUG

Sorry to resurrect this old thread but my parents have just had a WB Greenstart 28 cdi boiler installed yesterday. But my sister noticed while using the mixer taps in the bath that the water was getting hot and cold several times .

This is a brand new boiler , so I doubt there are any faults on the diverter valve or a faulty flow switch , or circuit board fault, or heat exchanger issue (scaling). We've fitted the WB magnetic filter and this is picking up enormous amounts of sludge (was cleaned on consecutive days while being tested). There was the mandatory pre-installation powerflush (that went on for 4-5 hours) which also removed an enormous amount of sludge.

Could it be that a certain amount of sludge still swirling away in the system has somehow not been picked up by the magnetic filter and caused a blockage in the exchanger channels?

I've searched through the internet trying to find similar issues and how they were resolved but found only one forum post that stated clearly what caused their issue (but could not be explained by WB experts who couldn't find a fault with the boiler).

The simple cure for this particular person's 'hot and cold ' showers was to reduce the flow of water from the mains to the boiler.

Maybe the fix is that simple so worth a try first before trial and error replacement of components.

JimmyChanga

On original turn of the tap the temperature may fluctuate for 20 seconds odd but then should stay constant. When did you last check the magnetic filter? From what I can understand this was installed before the boiler was?

HUMBUG

JimmyChanga wrote: »

On original turn of the tap the temperature may fluctuate for 20 seconds odd but then should stay constant. When did you last check the magnetic filter? From what I can understand this was installed before the boiler was?

The magnetic filter was part of the new installation and the plumber cleaned it on consecutive days (picking up quite a bit of sludge). He advised that I clean it every week for the first few weeks until it diminishes.

Actually , I've just got a reply from him regarding the hot and cold water. Here it is:

---

This time of the year the incoming water is very cold and it takes longer to transfer the heat from the exchanger into the water, the best way to deal with this is turn on the hot water and turn it down a little so that you are not getting the full flow of water this will insure a steady stream and you will not get the fluctuations, also if somebody opens a tap in a different location this cause the same thing to happen. It's all to do with the flow rate of the water coming in and the temperature of the incoming water.

See how you get on, if it's still a problem let me know.

---

I've advised my sister/parents to do the above and see what happens.

Another thing that has confused me is that when the plumber changed a washer on our dripping upstairs bath hot tap , he just switched the boiler off. There was no need to switch off the mains or an isolation valve. How can that be? I think he said (my hearing is very poor) that if you turned the mains off and then changed the tap washer , one might have to repressurise the system. :think:

I suspect when you switch off the boiler it shuts off any valve that facilitates any mains pressure in the hot water part of the system. I also suspect any flow of water out of the tap would have depended on the weight of water in the pipes above the tap (ie. gravity) vs outside atmospheric pressure on the tap. If the weight pressure was higher than 1 atmosphere, water would have flowed out of the tap when he dismantled it.

JimmyChanga

If you have the tap fully open the water may not be as hot but it should be constant.

As for cleaning the filter weekly - well, the heating flush wasn't done thoroughly enough.

You might have misunderstood the plumber who changed the washer on the hot tap. You central heating water is not connected to the hot tap's supply. But he may have isolated the cold water feed to the boiler. Therefore no water to hot taps that come off the combi.