Baxi Solo 2 - Weird Problem!

[Rabbit171]

Hi everyone, I've had a search and can't find any the answer, so I'm hoping one of you enlightened souls can help
I've got a Baxi Solo 2, wall mounted with a once/twice timer. It has a hot water tank in the airing cupboard, and two tanks in the loft. One tank I'm assuming is the for the hot water, the other (smaller one) is for the heating.
This is where it starts getting weird. When the heating and water is on nothing much happens. When you turn the heating off and leave just the hot water on, then hot water starts pouring into the tank from the (assumed?) heating overflow. This is on the smaller tank.
I'm afraid I don't know very much about Central Heating so please accept my apologies from the start Any help would be greatly appreciated, thanks

 

[Agile]

Sounds like a sludged up system!

Might need power flushing!

Tony

 

[ChrisR]

Yep - or just bad pipe layout.

 

[Rabbit171]

Cheers guys! Thanks a lot. I've got a chap coming to have a look this morning, I'll let you know what he says.

Once again, thanks for the advise

 

[Rabbit171]

Turns out that the pressure on the pump was too high. Turned it down and hark it has stopped, If it gets worse he says to clean it out.

Thanks for the advice