Why does shower pressure keep going up and down and hot and cold

[Derek Adamson]

Can anyone please help. We have shower issues and have had for about 2 years. We are in a farmhouse. So before hand, we would turn on our Trevi shower, it would go warm, not great pressure through the showerhead though, somewhere between normal and dripping! After a few minutes, the water flow would suddenly increase and the shower would go cold, then after 20-30 seconds the pressure would drop again and the heat would come back. Ut would just kep doing this whilst in the shower every few minutes. One plumber told me to replace the thermostatic valve, so I did. Didnt work. Then just before Christmas our external oil boiler, packed up. I got a brand new boiler fitted yesterday. Have just gone for a shower, flow still not great, took a bit longer this time but same again, water pressure suddenly increased, water went cold, for around 10 seconds, then pressure dropped back down and water went hot again. Stayed hot for about 5 minutes then did it again. I am at my wits end. Any ideas what is causing this?

 

[steadyon]

1. What sort of boiler. Make, model, combi / non-combi?
2. What sort of hot water system. Combi fed, cold tank in loft and hot water cylinder in airing cupboard, unvented hot water cylinder?
3. Make and model of shower? Presumably Ideal Standard but which model?

 

[Derek Adamson]

1. What sort of boiler. Make, model, combi / non-combi?
2. What sort of hot water system. Combi fed, cold tank in loft and hot water cylinder in airing cupboard, unvented hot water cylinder?
3. Make and model of shower? Presumably Ideal Standard but which model?

We had a Grant Combi Oil fired boiler and just put in a Worcester Greenstar Heatslave 32KW Combi. Hot water is fed from boiler, we have no tanks. The Shower, i am told, is a Trevi but it was here when we moved in and did work at one time with the Grant boiler. There is nothing to show what model it is.