New boiler and stat but room cool need advice please

[D_Hailsham]

Hi D Hailsham

Thanks for that
In that case wouid you think reducing the anti cycling time would help me

Don't see how it would help. The boiler flow temperature is set to 75C so, if the delay is set to 20 mins, the actual delay will be only one minute - according to the chart below from page 43 of the Installation Manual.

I thought you were installing a Hive in the place of the CM727. Is this still going ahead?

 

[2wd]

You'll have to excuse me if I say anything stupid about the set up as I'm gathering info off the net and then asking the experts.....ie you lot

Yes Hive today

 

[D_Hailsham]

You'll have to excuse me if I say anything stupid about the set up as I'm gathering info off the net and then asking the experts.....ie you lot

Yes Hive today

Let us know - in this topic - if the problem goes away when the Hive is working.

 

[2wd]

Let us know - in this topic - if the problem goes away when the Hive is working.

Had the hive fitted and put the disconnected CM727 at the side of it.
The CM727 is constantly showing 1.5 degrees higher temperature than the hive, so when we have been setting it to 21 it's been 19.5.
The hive is set to 21 and now we're a bit too hot
The room still cools down a bit but not to chilly
Plus the hive has the boost facility so 15 minutes boost brings the room temp back up again

 

[D_Hailsham]

The CM727 is constantly showing 1.5 degrees higher temperature than the hive, so when we have been setting it to 21 it's been 19.5.

Was the CM727 new when you obtained it? If not, the previous owner may have adjusted the stat because it was in a hot location. It's parameter 12:tO (temperature offset). Normally it should be set to 0.

 

[2wd]

Was the CM727 new when you obtained it? If not, the previous owner may have adjusted the stat because it was in a hot location. It's parameter 12:tO (temperature offset). Normally it should be set to 0.

Yes brand new
I emailed Honeywell and they also gave me the offset advice

 

[D_Hailsham]

Yes brand new

In that case, one of the thermostats is not telling the truth - or even both. Do you have a separate thermometer to compare them with (any DIY store should sell them)? The Hivehome website has several comments from users complaining about the inaccuracy of the Hive thermostat. I cannot find any spec giving the accuracy or the control limits of the device

As for having to boost the temperature every so often doesn't say much for the control ability of the Hive. It also suggests that the insulation in the house is not as good as you think.

 

[2wd]

My heating has only been on 45 minutes and the cm727 which I'm just using to compare is telling me it's 22 degrees in my living room which is total rubbish
I'll believe the hive which is showing 19 at present.
Actually just looking at insulation as well
We live in a bungalow and have 270mm of loft insulation but a couple of years ago had the loft above living room boarded over for use as storage space only but the builder just put the loft packs directly on joists therefore compressing the insulation.
I am wondering if I can just unscrew them and fit something like celotex between the joists then refit as I don't want to start having to raise it on the pegs

 

[OvertonPlumber]

Silly question. The radiator in the room does it have a trv on it??

 

[2wd]

Silly question. The radiator in the room does it have a trv on it??

No

 

[2wd]

To throw another quandary into this
Our house on a cool evening takes approx an hour to heat from 17 to 21 degrees.
When the stat shows 21 degrees, the heating goes off as it should and as per my OP the house goes too cool even though the stat says 21 degrees.
When the stat does eventually drop below 21, the hive drops in 0.1 segments so boiler kicks back in at 20.9 it takes ages to heat back up to 21 degrees which to me is proving that the true temperature of the house is much lower than indicated.
I'm now totally baffled

 

[2wd]

I emailed Vaillant tech support and got this reply.....
In the diagnostics menu, is the heating partial load set to auto D00. If so change it to manual KW as it may be struggling with the pipe work configuration

Now forwarded onto the installer awaiting a reply

 

[Grumpy Gasman]

Appliance configuration d.00 will be factory set to ‘auto’, remove ‘auto’ and adapt heat load to a suitable KW rating.

 

[2wd]

Ok but what does this actually mean
What effect will it have on the heating

 

[Grumpy Gasman]

When the boiler fires a symbol in the shape of a triangle will be seen on the left hand side of the boiler display screen, the boiler leaves the factory with d.00 set to ‘auto’.
With a hot water demand the ‘burner on’ symbol (triangle) will increase to the top of display screen showing the burner is @ full load (28kw). With a central heating demand and the boiler fireing you will notice the ‘triangle’ barely moves from the bottom of the display when d.00 is set to auto, if you were to change the setting from auto to 20kw the ‘triangle’ would increase meaning the burner has ramped up.
Changing partial load settings in d.00 has no effect on the HW output,