Baxi Combi 105e behaving oddly.....

[karnka]

We have a Baxi 105e and in the 8 months or so we've been in the house it's not been great.

The house is a small three bed semi, with probably just about enough radiators (most likely not too many for the boiler) but the heating has never performed very well.

Having the boiler heating the house, fully turned up, the house just about gets warm, just. When it's particularly cold even the hot water isn't _that_ hot.

Had a firm I've used before come and service it and take a quick look. They claim there's nothing wrong with it as such and that it's just not that efficient / doesn't perform that well. They didn't try to sell me a new one so I pretty much believed them (had a brand new Baxi Platinum in old house so perhaps I was spoiled so to speak).

Anyway, now the boiler is behaving even more strangely. The burner light is coming on when the heating is off and no water is being run, and then the pump is coming on for the central heating.

Basically, heating on when it's not supposed to be and no heating light to say that the boiler knows it's on. Can usually be fixed by flipping the boiler off and then on again but sometimes it needs to be left completely off for a while. This can still happen when the boiler is set to hot water only....

If anyone has any clue what's going on would be really grateful.

 

[Egga]

Is your boiler a 105e or a 105e instant?

 

[karnka]

Right - we've checked and it's a plain 105e.

 

[karnka]

Anyone?

 

[karnka]

Last try!

Looked through the forum and founds some bits and pieces that look a bit similar talking about the instant version but nothing that quite fits.

If anyone knows anything I would really appreciate it.

 

[namsag]

Usaully on a 105e if you are getting rads on with no heat or hot water demand then you have a faulty microswitch on the divertor valve ,it is sticking and thinks there is a hw demand and fires the boiler up and sends the heat around the rad circuit.

IF your rads are hot and the house is not then they are undersized and you need larger ones if they are only luke warm then the boiler is probably not set up correctly

 

[dazpara]

Best get a GSR bloke in to give it a service and he can check its pressures for you.

 

[karnka]

The micro-switch sounds like a plausible reason for the strange behaviour, the hot water light however doesn't come on in these situations so I'm not sure if that changes things....

On the subject of why it doesn't quite warm the house. I'm not certain there are quite enough radiators. The one in the living room is a bit undersized and the kitchen extension isn't terribly well insulated so could probably do with another radiator.

I'm not convinced that's the whole problem though. Although I would say the radiators there are do get hot (at least most of them) they don't get _burning_ hot. My old heating certainly did when it was turned up to full. There is also the fact that the hot water isn't that hot. What do you mean by the boiler not being set up properly. I'm interested.

About the pressure. The pressure in the heating does drop a little over time but is easy enough to top up. There isn't any noticeable difference in how the heating / hot water perform when it's fully topped up vs a little low on pressure.