DIY Doctor UK DIY Forums

Hello everyone,

I have just joined this forum today after reading the Q and A quite often.

I m very confused after just getting used to a combi boiler at our last property. I now have a water cylinder, a potterton profile boiler and agrundfro selectric ups 15-50 130 pump.

My problem is there have been two new radiators put in the conservatory which were plumbed directly in to a radiator in the lounge. So I have re-plumbed them to the inlet and the return pipes, but they still do not get hot. I have tried balancing the radiators and bleeding them but no luck. I thought about bleeding the pump, as when you open the cupboard you can hear air in the system. But do you do this with the pump turned on or off? I have 13 radiators in total so could it be that the pump is not strong enough? As another radiator has been fitted in the breakfast room, this making 3 extra since the system was ordinary fitted. If I fit thermostats to each radiator do I need to worry about balancing them, as I have four radiators with them fitted already?
I have drained the system and flushed water though it until the water ran clear.

I have three water tanks in the loft, of which one I think is an overflow tank as it is connected to the second one at the bottom, which then feeds the c/h. the third is my cold water tank. There seems to be a lot of pipe work in the cupboard were the boiler is housed. so from what I can make out the cold water feed comes in to the bottom of the water cylinder, there is another pipe comes out the other side which is hot and connected to a tee piece one end goes under the floor the other goes to the boiler with a valve on the top. Then half way up the cylinder I have a pipe is which is hot that two goes to a tee piece with a honeywell powerhead mid-position valve attached to it, one side goes under the floor and the other goes up to the pump, and then on to the boiler with a pipe through the ceiling to the over flow tank in the loft. Both of the pipes that go to the boiler are linked with 15mm pipe with a tap in the middle. There is also a tap above and below the pump, but when any of the three taps are turned they don't seem to move in or out. My pump is to hot to touch, and my boiler comes on about every 15 minutes.

One last thing should my hot water get heated when the c/h is on? Because it does seem to.

Sorry for all the questions but I have tried to give you all the info that I have, I am hoping that someone will have the magic answer.

Many thanks John.

I normally don’t answer post on this board, I think “diyâ€

phew- rather a tallorder. But firstly, is the boiler up to roducing the heat required?. Are the pipes of sufficient bore to carry the heat to where it is required? Then is the pump up tp overcoming the resistence.
You need to do calculations for this , based on heat losses, pipe losses, resistence on pipes. Heating Engineering is not picked up after a one hour session at evening classes. It is a science. Not easy to answer without all the facts :shock:

Dear Peter the plumber,

Many thanks for taking the time to respond to my questions. I think your answers were the ones I was expecting. In your opinion would I be better off replacing the system with a bigger boiler, cylinder, ect, or with a combi system. I mean ease of replacment and cost wise.

Once again
John Preston

Well sizing a boiler is hard to do without looking at the house.

Things like having kids in the house make a lot of different to the amount of hot water you need.

If there always someone in and the house need to be warm all the time makes a lot of different to the amount of heating you need.

You need to get a good plumber round and talk to him for about an hour, make sure he checks the radiators sizes for you, tell him how you use your home and then read the which reports on boilers.