Greenstar Condensing Boiler 24 Ri big enough for job?

davidw · Feb 4, 2020

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.

Chuck · Feb 4, 2020

davidw said:
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?

Scott_D · Feb 4, 2020

Vented or unvented cylinder?

magicno1 · Feb 4, 2020

It’s a regular heat only boiler not a combi to start 😀

davidw · Feb 4, 2020

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]

magicno1 said:
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.

centralheatking · Feb 4, 2020

davidw said:
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

EvilDrPorkChop · Feb 4, 2020

davidw said:
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?

davidw · Feb 4, 2020

EvilDrPorkChop said:
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.
[automerge]1580841527[/automerge]

centralheatking said:
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!

EvilDrPorkChop · Feb 4, 2020

davidw said:
No tank in loft, only cylinder on landing.
Cheers.
[automerge]1580841527[/automerge]

Will do!

Picture of cylinder might help.

davidw · Feb 11, 2020

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?

centralheatking · Feb 11, 2020

davidw said:
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

Keentolearn · Feb 11, 2020

The cylinder, does this have a cold tank sat on top?

moonlight · Feb 11, 2020

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.

davidw · Feb 12, 2020

moonlight said:
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.

Keentolearn · Feb 12, 2020

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.

EvilDrPorkChop · Feb 12, 2020

Keentolearn said:
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.

davidw · Feb 12, 2020

EvilDrPorkChop said:
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.

davidw · Feb 14, 2020

I've moved this thread to one under a better heading. Thanks for all the advice so far!!

ShaunCorbs · Feb 14, 2020

...... Closed ......

Welcome to PlumbersTalk.net

American Visitor?

Greenstar Condensing Boiler 24 Ri big enough for job?

davidw

Attachments

Chuck

Scott_D

magicno1

davidw

centralheatking

Plumbers Arms member

EvilDrPorkChop

davidw

EvilDrPorkChop

davidw

centralheatking

Plumbers Arms member

Keentolearn

moonlight

Plumbers Arms member

davidw

Attachments

Keentolearn

EvilDrPorkChop

davidw

Attachments

davidw

ShaunCorbs

Super Moderator

Similar plumbing topics