Two plumbing questions

Shelle

I have two questions relating to plumbing/water.

The first: We have had a new central heating system installed, a combination boiler. We have noticed that we get a loud knocking sound, in one room in particular, although can be heard around the house. We had it with the previous heating system, but not quite as bad as it is now. I can feel a "line" in the floor that is hot, which is presumably the pipe feeding the radiator in that room. Is there anything we can do ourselves? We dont appear to have floorboards in the sense of planks, but big blocks instead. Any advice???
do??
Second question: This was discovered when repairing a fault with newly installed boiler. When the water was turned off completely, it was discovered that water still ran out of the tap giving the implication that we have a second water source. Is this a problem? I wonder if it is inefficient as it means cold water is coming in as the boiler heats the water? If it is a problem, what can be done? We actually intend on renewing the bathroom sometime this year, can it wait till then, and what would a plumber do?

Sorry for the two rambling questions

ormus

the pipe banging is caused by the pipes expanding and moving. they need to be fixed more securely. which means lifting a section of flooring to get at the pipes.

need more info re the tap?
which tap and where?
and do you mean with the new boiler?

Shelle

When fixing new boiler (combination) which is in bathroom, they noticed that when water was switched off and to check this they ran the tap in bathroom sink which to their surprise continued to run. They said that should not happen as water was turned off so said we must have second water source. Dont know if that means it is in bathroom or not?

Incidentally, the hot water in bath does not get as hot as in other ensuite, so might indicate that cold water is mixing on with heated water from central heating system??????

Dont know if that is enough info, just ask again if need more!

ormus

assuming its the cold tap on the basin, then it could possibly have another feed to it from before the stopco ck you used to turn off the mains supply?
very unusual though.

Shelle

Is it anything to worry about though? Or is it just one of those quirky things?

ormus

it will be if you have a leak!
how do you turn it off!
you need to find out and then maybe fit another stopco ck thats stops all the water. ie where the water mains enters the building.

EliteHeat

Nip up to the loft and see if the cold water tank is still active. If it is, then it was a very, very shoddy installation.

ormus

i didnt suggest that cause i never thought anyone would do such a thing!
but we never stop learning and being amazed, do we!

EliteHeat

ormus wrote: »

i didnt suggest that cause i never thought anyone would do such a thing!
but we never stop learning and being amazed, do we!

I've seen it several times - always a shock though!

plumb1_2

EliteHeat wrote: »

Nip up to the loft and see if the cold water tank is still active. If it is, then it was a very, very shoddy installation.

Why would it be Shoddy work????? please explain .

EliteHeat

plumb1 wrote: »

Why would it be Shoddy work????? please explain .

Simple, unbalanced supplies. You should not have low pressure cold and high pressure hot water distributed to a property. The obvious exceptions to this are the rising main to the kitchen sink and purpose built taps such as venturi mixers.

When a property is converted to accept a combination boiler the cold water tank is decomissioned as a matter of course and the mains directed to all cold outlets, hence balancing the supply.

Ideally, the feed to the combi and to the cold water outlets should itself be balanced in the same way that manufacturers of unvented HWCs make available. In practise this doesn't normally happen, but the difference rarely makes a difference and if it does then the flow rate and water pressure were insufficient to justify a combi in the first place.