Half of the radiators not working

[James Bond]

Hi all,

I recently (a month ago) bought a house, and I am trying to understand how the heating/hot water system works. Apparently stuff got appended over time to it and the system is not functionning as best as it should.

First of all a description of the system (keep in mind I know nothing about heating systems, so apologies if some of it is obvious):

Let's start from the boiler, A Potterton Netaheat Electronic 10/16 Boiler, on the ground floor. From there a hot pipe goes up to an airing cupboard where it is connected to a pump. Before the pump two connections from the pipe are going to the attic, one at the bottom of a cold water tank and the other venting over it.

After the pump a T connection with a box on top split the flow in two, one side goes to the coil of a huge hot water tank, the other I assume goes to all the radiators in the house (I'm assuming it's some kind of valve). there is what look like a bleeding valve between the T connection and the hot water tank.

The pipe comming out of the hot water tank coil is connected to another that I'm assuming is the return from the radiators, and all this goes back down to the boiler.

There is a variety of controls on this system:

• 
  * A simple thermostat in the living room
  * A big button numbered from 1 to 4 on the boiler (set to 4)
  * Under the boiler a timer with two button, one for hot water, the other for heating. If you set heating on, hot water automaticaly come on as well.
  * A small button on the pump numbered from 1 to 3 (set to 3)
  * A slider on the side of what I assume is a valve.
  * A thermostat on the side of the water tank (set to 60)

My problem is that the radiators (13 of them) are not heating up properly. If I open all of them only the one upstairs are heating up, 5 of them scalding hot, and one warm, but not hot. All the downstairs one (6 of them) stay cold (no I know how to count, radiator 13 if off the circuit as it was leaking)

So far I've tried the following:

• 
  - Bleeding all the radiators. All of them had water up to the top (and the water was clear)
  - Turning off all the radiators but one. Eventually, after a while, all the radiators do become hot when isolated in this fashion.
  - Turning off a valve on the return of cold water from the hot water tank coil. This made the radiators heat faster, leading me to believe that either the valve is not working properly or that the hot water tank thermostat is not working.
  - I'm currently trying to balance the radiators as explained here. The radiator on the top floor that was only warm is now hot so it's getting better, however the downstairs one are cold still.

I asked a pro for advice an he came this morning to take a look around. He told me that I have to replace the boiler (too old, too small), the valve (seems broken) and all its controls pack and change all the radiator valves (they do look crusty). Add a power flush to this and I'll let you guess at the final price I was quoted.

Albeit his advice seems sound and is likely to fix all the issues, I'd like to know is how can I hack the system so it works nicely enough to last for the winter, without taxing my bank account that much.

First of all I'd like to know how the T connection valve is supposed to work, the one splitting the flow between the hot water and the heating circuit. What are the positions on the sliders? There is manual and auto printed on the side, but I can't seem to find a position where it would stop heating the water tank, even when the water in the tank is already hot. Is it by design? How would I go in testing this? What would I need to change to make it do so?

Would fitting thermostatic valves on the upstairs radiator help? I figure, once it is hot in the upstairs bedrooms the valve would cut the flow so there would be enough power to start the downstairs radiators right?

Any other idea on what I could try? I'm a fairly good DIY, but I don't have experience in plumbing at all. Thanks,

-- Eric

 

[kevplumb]

1 DONT SHOUT
2fully pumped system i assume
3is the 3 way valve working (dont sound like it )

 

[James Bond]

1 DONT SHOUT

I AM NOT SHOUTING BUT YOU ARE. Unless I misunderstood anything.

2fully pumped system i assume

I don't know really, as I don't know what a 'fully pumped system' is.

3is the 3 way valve working (dont sound like it )

I don't know, and my question is how do I test it? Is it normal to always have hot water going to the hot water tank coil, even when the tank is warm enough?

 

[kevplumb]

would assume if you have a tank stat there is a zone valve or diverter valve somewhere in the system (airing cupboard )
when the stat gets to temp it should cut the flow to the cylinder
if not dodgy valve or stat

 

[James Bond]

There is no valves in the cupboard but the T one I've described. And no matter the temperature of hot water at the faucets there is always hot water going to the cylinder coil. I'm going to play with my tester tomorrow and see if the thermostat works, and what kind of juice come to the valve. Maybe hitting hit with a mallet a couple of times, just for kicks! It may unlock something.