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We've just moved into a house with the Greenstar condensing boiler. It seems to be struggling a little in that if you're running a bath and someone puts the dishwasher on then it's as if it can't cope. We've come from a combi Boiler and this seems a little ropey in comparison. Maybe I'm expecting too much from this type of boiler? any advice appreciated.
 

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It seems to be struggling a little in that if you're running a bath and someone puts the dishwasher on then it's as if it can't cope.
What exactly do you mean by "can't cope"? Can we assume that the dishwasher is not plumbed into the hot supply? If so, the problem is more likely to be the capacity of your incoming water supply and/or the pipework feeding the boiler and dishwasher.

Anyway, lets start with the simple stuff, is the stop-cock properly open?
 
I think you may be right about the capacity of the incoming water. I've made sure the stopcock is turned fully on. If I'm running several hot water taps then the system seems to struggle with producing enough water. I thought it might be the boiler not able to heat enough to meet demand, but the more I think of it, the water pressure does seem low.
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It’s a regular heat only boiler not a combi to start 😀
Yes, as I said, we moved from a combi to this condensing boiler.
 
I think you may be right about the capacity of the incoming water. I've made sure the stopcock is turned fully on. If I'm running several hot water taps then the system seems to struggle with producing enough water. I thought it might be the boiler not able to heat enough to meet demand, but the more I think of it, the water pressure does seem low.
[automerge]1580832532[/automerge]

Yes, as I said, we moved from a combi to this condensing boiler.
Go to the outside tap and discharge a monitored volume of water over 1 min and see what volume.
Do this at peak time just before school on a weekday, again in the evening peak and about 6am on a Sunday and let us know what you find. Just check the outside tap is on the mains There is a relationship between pressure and volume but you are looking at volume Centralheatking
 
I think you may be right about the capacity of the incoming water. I've made sure the stopcock is turned fully on. If I'm running several hot water taps then the system seems to struggle with producing enough water. I thought it might be the boiler not able to heat enough to meet demand, but the more I think of it, the water pressure does seem low.
[automerge]1580832532[/automerge]

Yes, as I said, we moved from a combi to this condensing boiler.
That’s because you’ve probably got a gravity fed hot water cylinder and not a pressurised system. Have you got tanks in your loft?
 
That’s because you’ve probably got a gravity fed hot water cylinder and not a pressurised system. Have you got tanks in your loft?
No tank in loft, only cylinder on landing.
Cheers.
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Go to the outside tap and discharge a monitored volume of water over 1 min and see what volume.
Do this at peak time just before school on a weekday, again in the evening peak and about 6am on a Sunday and let us know what you find. Just check the outside tap is on the mains There is a relationship between pressure and volume but you are looking at volume Centralheatking
Will do!
 
Hi, I've measured the output and it's averaging at 1 litre per 10 seconds. That's with nothing else being used. Is this low?
 
Hi, I've measured the output and it's averaging at 1 litre per 10 seconds. That's with nothing else being used. Is this low?
6 litres per min is above the statutory min. Your utility have to supply but it won’t be enough to much more than one use around the house at one time. There are totally legal booster pumps but when your neighbours all get one it’s back to square one. You might try installing a new supply from the utility to your house, but if it’s a long way it’s a lot of digging and has to be inspected. Centralheatking
 
Sounds like you may have an unvented cylinder, or a thermal store. You may need someone who is qualified to look at this problem. Pictures would be useful. Thanks.
 
Sounds like you may have an unvented cylinder, or a thermal store. You may need someone who is qualified to look at this problem. Pictures would be useful. Thanks.
Here's a photo of the cylinder.
 

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See how the cylinder has a small section at the top, that’s a cold water storage cistern, Known in industry as “fortic”. That’ll be your problem, check to see how quickly water is replenished as hot water is Drawn off.
 
See how the cylinder has a small section at the top, that’s a cold water storage cistern, Known in industry as “fortic”. That’ll be your problem, check to see how quickly water is replenished as hot water is Drawn off.
It’s not a combination cylinder it’s a thermal store. The tank is supplying the heating side of the system.

The strainer is probably blocked on the incoming main, where the expansion vessel is. It’s not clear if there’s a PRV on the incoming main on the photo but if there is I’d check that this is operating correctly too.
 
It’s not a combination cylinder it’s a thermal store. The tank is supplying the heating side of the system.

The strainer is probably blocked on the incoming main, where the expansion vessel is. It’s not clear if there’s a PRV on the incoming main on the photo but if there is I’d check that this is operating correctly too.
here are a few more photos. Thank you for all the advice - it's much appreciated.
 

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...... Closed ......
 
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