HW & CH not working at the same time? (WB 30CDi)

[Brownjamesa]

Hi,

I have recently had a new boiler installed (July 2010) and have only just released that the boiler is running either the CH or HW function one at the time and not both together.

I have got the DT20 timer, and have setup my program as follows:

HW:
M-F: 06:00-07:00 | 17:00-18:00
S-S : 06:00 -07:00 | 17:00-18:00

CH:
M-F: 06:00-08:00 | 17:00-22:00
S-S : 07:00 -10:00 | 16:00-23:00

I have the following CH/HW setup:

Boiler:
WorsterBosch Greenstar 30DCi Boiler (60/100 Horizontal Flue)
DT20 Timer | Intergral Diverter Value

HW Cylinder:
GLEDHILL 1500X450 INDIRECT COPPER CYLINDER
POLYTANK LOFT TANK 64X24X19 70G
Stuart Turner Monsoon Standard 3.0 Bar Twin Pump

Installation Layout:
S-Plan:

Untitled

• Brownjamesa
• 13 Dec 2010
• 1

When I walk down stairs in the morning (06:15), the boiler is on and is heating the HW Cylinder (readout displays 85 ish) but the radiators are cold, if I press the “advanced” button to turn off the HW, the readout goes straight down to 30-40 ish, then the boiler kicks in about 2 mins, then starts heading the radiators…

Is there a problem with the diverter value?, as I was under the impression that the boiler could heat the HW cylinder and CH at the same time?

If it can’t then I will just have to re-arrange the HW & CH times, so they don’t come on at the same time (My old Potterton NeatHeat 10-16 could)

Cheers
James

 

[stem]

If you have a three port valve......

Untitled

• stem
• 1 Apr 2010
• 8

.....and only hot water or central heating can work at any one time, that suggests to me that the valve actuator is travelling from one end to the other, but not taking a central position which would allow both hot water and central heating to work together.

So my guess is that either the system has been wrongly wired up since July, but you haven't noticed because by the time you got up the hot water cylinder was heated up and the system had switched over to the radiators, or there is a fault with the motorised valve. (It has an integral microswitch that keeps it in the centre position)

You are correct in your assumption, that you should be able to have both working together. This is one advantage of a traditional "heat only" boiler over a "combi".

 

[Brownjamesa]

Cheers Stem,

I dont remenber having one of those 3 port valves installed.

Without that 3 port value installed, is that the reason why it doesn't do HW & CH at the same time?

James

 

[Hugh Jaleak]

3 port valve is used on a 'Y' plan, 'S' plan uses 2x 2port valves. Same end result, just a different set up. How many pipes do you have running from the boiler?

 

[ChrisR]

Even with two 2-port valves (S plan) it could have been wired so HW has priority.

I assume you meant 30 CDi, I don't know of a DCi
Using a combi such as yours with a separate cylinder needs slightly unusual wiring, so there's plenty of opportunity for yer average joe to cock it up..
It's possible the fellah did it that way on purpose, if the boiler heating capacity is marginal for the radiators you have.

You said integral diverter valve - note that that's for the combi's hot water on-demand output (kitchen sink, perhaps), not for the stored hot water in your cylinder.

 

[D_Hailsham]

Worcester Bosch Greenstar 30DCi Boiler (60/100 Horizontal Flue)
Intergral Diverter Value

Installation Layout:
S-Plan:

Untitled

• Brownjamesa
• 13 Dec 2010
• 1

The Integral Diverter valve is what it says: it diverts the water to either the central heating or to the hot water. You can't have both at the same time.

The DT20 and the Diverter valve work as a pair; you can't have one without the other on a System boiler.

 

[Brownjamesa]

Hugh,

I have 6 pipes that are coming from the boiler from memory:

HW Feed
HW Return
CH Feed
CH Return
Gas
White plasic pipe to internal waste

Chris,

You are correct, it is the CDi

I do have the integral diverter value, as I have the following manuals:

Untitled

• Brownjamesa
• 13 Dec 2010
• 1

Cheers
James

 

[Brownjamesa]

D_Hailsham,

Thanks for your response, so the system is working as designed.

If thats the case, I will just program the HW to come on and off before I want the CH to come on.

 

[D_Hailsham]

If that's the case, I will just program the HW to come on and off before I want the CH to come on.

WB Recommend the FR10 Intelligent Thermostat with the Diverter valve.

What temperature is the boiler set to?

What temperature is the Hot water set to?

 

[Hugh Jaleak]

I was trying to ascertain whether the diverter valve was external or internal.

Does seem a bit of a backward step to me if you cant heat HW and CH together? (No good here, I have a teenage daughter who likes to be warm and empty the HW cylinder into the bath on a regular basis!)

 

[Brownjamesa]

If that's the case, I will just program the HW to come on and off before I want the CH to come on.

WB Recommend the FR10 Intelligent Thermostat with the Diverter valve.

What temperature is the boiler set to?

What temperature is the Hot water set to?

CH: Max
HW: E

 

[Brownjamesa]

I was trying to ascertain whether the diverter valve was external or internal.

Does seem a bit of a backward step to me if you cant heat HW and CH together? (No good here, I have a teenage daughter who likes to be warm and empty the HW cylinder into the bath on a regular basis!)

There is only two of us, and we have a lot of stored HW with a 3 par pump to feed two showers.

I am thinking of re-programing the timer as per below:

HW:
M-F : 05:00 - 05:45 | 15:00 - 15:45
S-S : 05:45 - 06:30 | 15:00 - 15:45

CH:
M-F : 05:45 - 08:00 | 15:45 - 22:00
S-S : 06:30 - 10:00 | 15:45 - 23:00

 

[Brownjamesa]

If that's the case, I will just program the HW to come on and off before I want the CH to come on.

WB Recommend the FR10 Intelligent Thermostat with the Diverter valve.

What temperature is the boiler set to?

What temperature is the Hot water set to?

I have an standard honeywell thermostat, with the existing wireing already there, could I install the FR10?

Also, what other benifits would it give me apart from the LED display (Which would look cool )

 

[stem]

Cheers Stem,

I dont remenber having one of those 3 port valves installed.

Without that 3 port value installed, is that the reason why it doesn't do HW & CH at the same time?

James

The boiler manual in the link below, shows that it can be installed with a 3 port valve to give CH & HW simultaneously.

Click here for the manual. The 3 port valve is shown on page 10 "Y Plan Layout"

If yours is fitted with an internal diverter that only offers two positions, it looks like they are using the parts from the combi version and introducing combi disadvantages.