Worcester Bosch 35CDi Hot water problem - no flow

[Trouty]

Hi, turned on my hot tap this morning and nothing came out, just a trickle. Cold water tap flowing fine, so I assume water is actually entering the house and feeding the boiler. Bathroom hot water tap the same - then it flowed as normal then reduced to a trickle again.

Don't know if it's coincidence or not but I reduced the hot water temperature setting to minimum on the boiler and the flow started as normal. Put it back onto it's normal temperature setting of about 3 and it's been ok since then. Can anyone suggest what my problem may have been please as I guess it's the start of something that will need to be looked at

 

[aggis]

Is any of your hot pipes exposed, near a air vent? not lagged. Frozen? Had this a few times this winter.

 

[Trouty]

Only in the cupboard where the boiler is, which is on an outside wall but I would doubt gets anywhere near freezing. We're in a bungalow and from the cupboard the pipes go to the loft, but all pipes are lagged up there. Saying that it is absolutely bitter cold in the loft as I went up to get the Xmas deccies down