Hi everyone just looking for some advice or information regarding my boiler. I moved into my flat 2 years ago the previous combi gas boiler was a Glow Worm Flexicom cx30 and the one I have had for around 18 months is a 20KW Vokera Easi Heat Plus combi boiler. The DHW is okay but not as consistent as it could be for example I took readings of the hot water and it ranged from a minimum of 34 degrees to 55 maximum. So my question is that is the 20KW too small of a boiler for my flat, the manual states a min of 35 and max of 60 degrees for DHW, is this normal for boilers.
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Discuss Is boiler too small 20kw? in the Boilers area at Plumbers Forums
You can get about 6.4 litre per minute of water heated from 10°C to 55°C from a 20kW heater. If you increase the flow rate to 11.4 litre per minute the temperature rise reduces to 25°C, i.e. 35°C DHW.
If you haven't got an 'eco' spray on your shower it would be worth getting one. A bath will take about 10 mins to run, which is a bit slower than most people would want.
If you haven't got an 'eco' spray on your shower it would be worth getting one. A bath will take about 10 mins to run, which is a bit slower than most people would want.
I took readings of the water temperatures in the bathroom both tub and basin have mixer taps and kitchen which also has a mixer tap. Do these reading seems in any way odd or is this normal for a gas boiler, this would really help me as I try to learn and understand how things work thanks.
20KW Vokera Easi Heat Plus combi boiler, boiler is 7 meters away from bathroom.
No single/double check valves or NRV installed in any of the pipe works.
One stopcock under the sink, one red gate valve in a cupboard outside and above bathroom door.
The DHW dial doesn't have any led or numbers to indicate the temperature but instead has 10 dots around the dial, the following are the hot water temperatures in Celsius. dot 1 lowest temp, dot 10 highest.
Dot 1 to dot 10 DHW temps
Dot 1 Kitchen 35 c Dot 2Kitchen 34 c Dot 3Kitchen 39 c Dot 4Kitchen 41c Dot 5 Kitchen 43 c
Dot 1 Bathtub 24 c Dot 2Bathtub 26 c Dot 3Bathtub 28 c Dot 4Bathtub 31c Dot 5 Bathtub 41 c
Dot 1 Basin 40 c Dot 2Basin 38 c Dot 3Basin 26c Dot 4Basin 36 c Dot 5 Basin 32 c
Dot 6 Kitchen 46 c Dot 7 Kitchen 45 c Dot 8 Kitchen 55 c Dot 9 Kitchen 56 c Dot 10 Kitchen 51c
Dot 6 Bathtub 42 c Dot 7 Bathtub 38 c Dot 8 Bathtub 39 c Dot 9 Bathtub 41 c Dot 10 Bathtub 40c
Dot 6 Basin 32 c Dot 7 Basin 42 c Dot 8 Basin 44 c Dot 9 Basin 51 c Dot 10 Basin 42c
I ran the bathtub hot and cold water and timed how long it took to fill a 8 litre bucket:
Cold water filled bucket 8 litres in 20 seconds
Hot water filled bucket 8 litres in 1 minute
20KW Vokera Easi Heat Plus combi boiler, boiler is 7 meters away from bathroom.
No single/double check valves or NRV installed in any of the pipe works.
One stopcock under the sink, one red gate valve in a cupboard outside and above bathroom door.
The DHW dial doesn't have any led or numbers to indicate the temperature but instead has 10 dots around the dial, the following are the hot water temperatures in Celsius. dot 1 lowest temp, dot 10 highest.
Dot 1 to dot 10 DHW temps
Dot 1 Kitchen 35 c Dot 2Kitchen 34 c Dot 3Kitchen 39 c Dot 4Kitchen 41c Dot 5 Kitchen 43 c
Dot 1 Bathtub 24 c Dot 2Bathtub 26 c Dot 3Bathtub 28 c Dot 4Bathtub 31c Dot 5 Bathtub 41 c
Dot 1 Basin 40 c Dot 2Basin 38 c Dot 3Basin 26c Dot 4Basin 36 c Dot 5 Basin 32 c
Dot 6 Kitchen 46 c Dot 7 Kitchen 45 c Dot 8 Kitchen 55 c Dot 9 Kitchen 56 c Dot 10 Kitchen 51c
Dot 6 Bathtub 42 c Dot 7 Bathtub 38 c Dot 8 Bathtub 39 c Dot 9 Bathtub 41 c Dot 10 Bathtub 40c
Dot 6 Basin 32 c Dot 7 Basin 42 c Dot 8 Basin 44 c Dot 9 Basin 51 c Dot 10 Basin 42c
I ran the bathtub hot and cold water and timed how long it took to fill a 8 litre bucket:
Cold water filled bucket 8 litres in 20 seconds
Hot water filled bucket 8 litres in 1 minute
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Someone get John.g, he loves numbers!
Is it 20kw heat and 25kw hot water ?
35 deg rise at 10.2 litres per min spec.
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The smallest Vokera Easyheat combi I found is 25kw which should give an adequate flowrate for a one bathroom/kitchen flat but slightly less than your previous 30kw rated boiler.
Those analogue dials aren't particularly accurate and so you get the largest HW temp rise in the kitchen as it's nearest the boiler all the while the bathroom is 7 metres away so max HW temp is lower which you'd expect and you've demonstrated. Try insulating the HW pipe to the bathroom if it's accessible and it hasn't been.
Those analogue dials aren't particularly accurate and so you get the largest HW temp rise in the kitchen as it's nearest the boiler all the while the bathroom is 7 metres away so max HW temp is lower which you'd expect and you've demonstrated. Try insulating the HW pipe to the bathroom if it's accessible and it hasn't been.
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"Hot water filled bucket 8 litres in 1 minute"
If 20kw output. deltaT= 20*860/8/60, 35.8C, with 8C CW temp= HW temp of (35.8+8), 43.8C
If 25kw output. deltaT= 25*860/8/60, 44.8C, with 8C CW temp= HW temp of (44.8+8), 52.8C
DHW performance is normally given at a deltaT of 35C so...
flowrate at 20kw=20*860/35/60=8.2LPM
flowrate at 25kw=25*860/35/60=10.2LPM
Some boilers have a selectable DHW temp so ensure that this is set to max, normally 60C? to get maximum Flow temp performance.
Thank you for the replies and I am better informed now about the boiler. I took a few pictures for some other information and the side of the boiler states 20KW.
Does the pipe work connected to the boiler seem about right?
The hot water pipe under the sink (top pipe) has a valve on it with the number 15 on it and the cold pipe (under top pipe) has a stopcock which stops the water coming into the kitchen sink. Does the cold pipe need a valve on it as I don't know what kind of valve the hot pipe has on it.
The basin in the bathroom has two pipes for the mixer tap, with isolation valves does it seem right, no valves required?
The cupboard outside the bathroom and above the door has two pipes coming into the flat, main cold water feed pipe with a 22 mm NRV on it which has the red gate valve which is fully opened, does it need to positioned fully open?
The hot water pipe next to the main cold water feed pipe has no NRV does it need one or is it fine the way it is.
Any information as always would be appreciated, thank you.
Does the pipe work connected to the boiler seem about right?
The hot water pipe under the sink (top pipe) has a valve on it with the number 15 on it and the cold pipe (under top pipe) has a stopcock which stops the water coming into the kitchen sink. Does the cold pipe need a valve on it as I don't know what kind of valve the hot pipe has on it.
The basin in the bathroom has two pipes for the mixer tap, with isolation valves does it seem right, no valves required?
The cupboard outside the bathroom and above the door has two pipes coming into the flat, main cold water feed pipe with a 22 mm NRV on it which has the red gate valve which is fully opened, does it need to positioned fully open?
The hot water pipe next to the main cold water feed pipe has no NRV does it need one or is it fine the way it is.
Any information as always would be appreciated, thank you.
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Can't comment on the installation set up.
Have you got two temperature dials (with dots) on your boiler, if so one will be marked CH and the other DHW?. If only one dial then this I would think only controls the CH (rads) temperatures and the DHW temp will/should give a max of 60C depending on the flow rate, 20kw will give a max flowrate of 5.5 LPM at this temp, so suggest adjusting any hot tap to give this flowrate and measure the temp at say dot1, this will tell you if this "knob" is controlling the DHW temperature or not.
Have you got two temperature dials (with dots) on your boiler, if so one will be marked CH and the other DHW?. If only one dial then this I would think only controls the CH (rads) temperatures and the DHW temp will/should give a max of 60C depending on the flow rate, 20kw will give a max flowrate of 5.5 LPM at this temp, so suggest adjusting any hot tap to give this flowrate and measure the temp at say dot1, this will tell you if this "knob" is controlling the DHW temperature or not.
Yes I have two temperature dials on the boiler one for DHW and then other for the central heating, both dials are the same with 10 dots around it. On dot 1 the minimum temp I get from the hot water is 35 and the max 40. Maybe my boiler is a bit rubbish then as I went along with a sales pitch without the company coming to my flat to see the pipe works layout unless it is just okay.
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Don't think there is anything wrong with your boiler or the pipework, the 20kw boiler will give a temperature rise of 35.8C at 8 LPM so IF the cold water temp is 8C then the HW temp is 44C, or just take the CW temp and add it to 35.8C., you got a temp of 42C which suggests a CW temp of 6.2C. A 30 kw boiler would give you a flowrate of 12.3 LPM under the same conditions
If dot1 is 35C then the boiler should control to that temperature below a flowrate of 10.6 LPM and so on, if the SP is 45C then it should control to that temp below a flowrate 7.7 LPM.
If dot1 is 35C then the boiler should control to that temperature below a flowrate of 10.6 LPM and so on, if the SP is 45C then it should control to that temp below a flowrate 7.7 LPM.
Excellent thank you. The 30kw boiler was around 14 years and the previous owner said it needed replacing as it hadn't been serviced in a few years either. She gave me contact details of a family business and engineer who would provide me with a new boiler and radiators.
So when I called engineer he took a few measurement details down then supplied and fitted the boiler and radiators. I had no idea about boilers at all or anything to do with pipe works related to such things however being on this forum has both educated and having people such as yourself help advise me better, thank you.
Perhaps in the future if I need to replace the boiler I will be smarter about it and take onboard the advice given so far.😀
So when I called engineer he took a few measurement details down then supplied and fitted the boiler and radiators. I had no idea about boilers at all or anything to do with pipe works related to such things however being on this forum has both educated and having people such as yourself help advise me better, thank you.
Perhaps in the future if I need to replace the boiler I will be smarter about it and take onboard the advice given so far.😀
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