I have a hot water boiler mounted on the wall (not sure of make) which produces immediate hot water around the house and also acts as the boiler for the radiator heating system. I presume the cold water coming into the boiler comes from the mains, but I'm not sure. As regards the cold water, I have a cold water tank in the loft.

I hope this sufficiently sets the scene!

My problem is that when I turn the hot water tap on in the kitchen (and the boiler fires up OK and I get nice hot water from the sink tap) and then also turn the hot water tap on in the bathroom sink or even the actual bath hot water tap, no water comes out of the bathroom sink tap or the actual bath tap. In other words I can only have one tap on at a time in the house, which is not very satisfactory.

Can anyone let me know what the problem is. I've never come across this before in all the houses I've owned.

Do you have shut off valves under that sink with no water? If so, shut down your main and open the shut off connection between the valve and the pipe coming out of the wall. Have another person slightly open the main while you are prepared to catch water in a bucket. Was there ample supply of hot when you do this? Could be a clogged faucet cartridge.

Saratops,
Tell me more about this "boiler that mounts on the wall" and produces hot water for both heating and bathing. Sounds like a insta-hot on demand water heater but It takes a constant flow to heat a house so you have some explaining to do before we go much farther. Are you in the UK? Let me know . Tom

Thanks to all responses. I have done some more checks and seems whoever put new boiler and central heating system in, put wrong size pipes to connect hot water from boiler. Should be 22mm pipes whereas mine are 15mm, so pressure is much lower. Will get plumber in to quote for work and hopefully all will be resolved.

Thanks again

Saratops,
Thanks for the update. Let us know if you need assistance in the future. Cheers, tom