Hot water issues.

[a4007035]

We have an S-Plan unvented central heating/water system with a hot water cylinder. The boiler is set to come on twice daily: Once in the morning at 6:30am-8am (1 hr 30) and once in the evening at 5-7pm (2 hrs). The boiler heats the water and central heating at the same time.

I got up the other morning around 7:15am for a shower. so the boiler would have been on for 45 minutes. However, the hot water was tepid. I appreciate its been cold recently but I thought after 45 minutes the water would have been up to temperature. Im normally in the shower at 7:45 and the hot water is fine.

We just got back from the in-laws this evening and the childrenwere really tired so we decided to give them a bath around 6:30pm. Again the water was luke warm (not suitable for a child's bath). So we had to put the immersion on to quickly get it to temperature.

I think it could be a number of things but looking for pointers on where to start first???

1. I heard that the radiators for the central heating may be out of balance. Could this be it? We did have TRVs fitted recently and I imagine the plumber would have had to play around with this. However, I always thought that with an s-plan system the water for the central heating just runs through the coil in the hot water cylinder which indirectly heats up the hot water in the cylinder.
2. I read somewhere that it could be the balancing valve on the hot cylinder. But Im not sure where this is?
3. Is the boiler temperature set right? We recently had it serviced and the engineer had set it to 65C so I don't think its that.
4. Could it be the cylinder isnt insulated? Is there any way to check whether it is insulated? Im pretty sure it is, house was built in 2007. But I was tempted to put some insulating jacket on the outside and on the pipes too which are bare.

In the summer, we turn down the 2 central heating thermostats.

Any help would be really appreciated.

 

[JonathanM]

I have an S-Plan, too.

45 minutes might not have been enough time to get the water hot enough when you had your shower, but the hour and a half before the baths should have been.

The first test I would do would be to turn the central heating off, and just turn the hot water on by itself. Start by checking if the boiler fires up. If the boiler has been on for the heating, it might not come on for half a minute or so whilst the boiler cools down. Leave the hot water on for an hour and see if you get a hot cylinder of water. Whilst that's happening you could also check how long the boiler burns for before cycling off, and check the pipes flowing into and out of the cylinder to see if they are getting hot.

EDIT: another obvious thing is to check the cylinder thermostat, to make sure it's not been turned down by mistake!

 

[terryplumb]

If the system historically worked fine ,then something has recently changed,the boiler temp was changed for instance. How soon after that did you start having the issue with hot water?
Do you know what temperature was previously set ?
Could be unrelated of course .