Only 6 minutes of hot water from cylinder

[swinstaller]

Hi guys, I wonder if any of you have any ideas on this one.

I was asked to carry out a powerflush on a heating system at a rented property as all the rads had cold spots, were not getting hot etc. Whilst chatting to the tenant he told me that he was only getting roughly 6 minutes of hot water from his hot water tank when he showered. So, when I had finished the flush I turned the hot water to 'on' to heat the tank up.

During the 40 minutes that it was on I noticed that the boiler was firing for 5 minutes at a time with roughly 30secs - 1 minute gaps. After the 40 minutes I ran the hot water via the shower head and only received 6 minutes of hot water.

The intermittent firing does not occur when only the central heating is on and as I had a spare cylinder stat in the van I changed the existing one but to no avail.

apparently it's only been a issue in the last 4 weeks or so.

Any ideas as to why this might be happening?

 

[Agile]

Make and model of boiler and temp and power setting?

Flow and return temps at cylinder?

 

[NuaghtyNigel]

Sounds like a scaled cylinder cylinder to me.

I agree. The boiler is heating the water in the primary circuit, but the heat isn't going anywhere. I know the London area suffers quite badly with hard water and scaling on heating elelents. If you can get the immersion heater out you can have a look inside to see if we are right!

NN

 

[Dan Robinson]

Sounds more like a blocked tee on the feed from the header tank.

 

[swinstaller]

Thanks for the replies guys.

To be quite honest I did think scaled cylinder. The cupboard that it is located in is tiny and it's going to involve cutting pipework to get it out to check if it's scaled. Is there any other way of confirming this suspicion?

 

[Agile]

Make and model of boiler and temp and power setting?

Flow and return temps at cylinder?

 

[xr4x4]

Can you see any other restrictions on the HW flow pipes? A gate valve for example that might have been played with?

 

[Norcon]

Its probably a sludge bucket.

 

[swinstaller]

Not sure on flow and return temps, I didnt have my thermometer when I was there. I'm back there on Monday to address the hot water situation so I'll have more info then.

Yes, there is a cylinder lockshield but it seemed to be in good working order as I closed and opened it when I was carrying out the power flush.

 

[xr4x4]

Not sure on flow and return temps, I didnt have my thermometer when I was there. I'm back there on Monday to address the hot water situation so I'll have more info then.

Yes, there is a cylinder lockshield but it seemed to be in good working order as I closed and opened it when I was carrying out the power flush.

So the lockshield is fully open?

 

[Tipper]

I fitted a new cylinder a few years ago due to lack of HW and it was so full of scale when I removed it I couldn't pick it up!

I had to slide it down the stairs and roll it to the door!

 

[HERTS P&D]

Tell the landlord he needs a new cylinder. Any money he spends on his property will come off his tax bill.

Andy

 

[Whitespirit66]

I fitted a new cylinder a few years ago due to lack of HW and it was so full of scale when I removed it I couldn't pick it up!

I had to slide it down the stairs and roll it to the door!

Suppose that's why the scrappie gives a fixed price per cylinder. Doesn't want to get caught buying several pounds of minerals.

The hard water in Bristol must add a bit to the weight of each cylinder.

 

[Phill Peck]

I fitted a new cylinder a few years ago due to lack of HW and it was so full of scale when I removed it I couldn't pick it up!

I had to slide it down the stairs and roll it to the door!

Suppose that's why the scrappie gives a fixed price per cylinder. Doesn't want to get caught buying several pounds of minerals.

The hard water in Bristol must add a bit to the weight of each cylinder.

Never been to a scrapie that has set prices always weighed

 

[Whitespirit66]

I'll have to change my scrappie then.