Help - hot water issues on gravity controlled system

[hit0062]

Hi - would really appreciate some help/advice here. I'm new to this forum and inexperienced in the world of plumbing.

I have the old conventional style heating setup at home with a hot/cold water tank in the loft, a cylinder in one of the upstairs room and the boiler downstairs in the kitchen. It is a gravity hot water and pumped central heating system.

I have the following problems that I'm sure are related.
1) If I switch on CH/HW together, the heating comes on fine but the water is taking excessively long to heat up. Only if I crank up the boiler thermostat to the max will I get sufficiently hot water for a shower etc.
2) If I switch on the hot water on it's own - I do not get get hot water despite hours of waiting.
3) 2 of my upstairs radiators are warming up but when I bleed them they remove some of the air bubbles and then simply stop - no water comes out.

I'm not sure if my pipes are blocked with sludge or there is an air gap or there is something more sinister here. My questions:
1) Any ideas what this may be and how I can try fixing it?
2) Some people have suggested I "power flush" my system. I'm trying to research into the pros/cons of this but thought I'd ask the experts what the probabilty of leaks etc is through power flushing. I'm just concenred that it's a rather old setup and if the pipes etc are not able to handle the excessive water pressure in the cleaning process, then I may end up with more problems with leaking pipes etc.


Anyway, appreciate in advance all help/advice!

 

[powell33]

hi there hit0062 it seems that you have a primatic cylinder and it sounds like the air bubble is removed. Try draining down just the cylinder then refilling it. this should restore the air bubble or you might have an airlock on the flow and return pipes to cylinder

 

[ecowarm]

If you have two tanks in the loft, 1 large and 1 small I think that the ball valve may be stuck. Have a look and the tank may be dry, move the arm up and down a few times and the system will refill.

Eco

 

[aggis]

Hi, when bleeding Rads turn the system off, as if the pump is on, you could be drawing air into the system.
If you've only got 1 large tank in the loft, your cylinder is a Primatic. You could test the flow & return pipes with a magnet, if it sticks it's blocked [Magnatite]. Turn water off, open hot taps, drain central heating system, cut out sections of the flow & return pipes from the cylinder, checking for blockages.

If 2 tanks, a large & small.
If you've checked the small tank & it's full, you've probably got a blockage in the DHW circ's. But 1st check that the cold feed valve is turned on.
On your cylinder the flow is directly above the return, the cold feed pipe 15mm pipe will go into the return, this is a favourite place for blockage.
[It is possible for the whole flow & return to be blocked.]

Probably best to drain system.
Then start by disconnecting return on cylinder, check for blockage,if so cut out pipes gradually back towards boiler until you find the pipe clear. If you only find around where the cold feed connects, cut out cold feed & clear blockage.

Fill system & test, if all works ok, would recommend to clean system with chemicals, Sentinel X400 or similar. Leave in system for maxium of a month, frequently using the heating [rads] as well. then drain, refill, flush & finally fill with inhibitor X100.
Powerflushing the system can be done, after removing the blockage, but if using stronger chemicals check they're suitable for your type of boiler.
From what you describe just powerflushing the system without finding the blockage, would be awaste of time & money.

Get a professional if in doubt,
Also Don't get any of the Magnetite on your carpets if you descide to give it ago! You'll also need a professional carpet cleaner.
Good luck

 

[easyt]

If you have two tanks in the loft, 1 large and 1 small I think that the ball valve may be stuck. Have a look and the tank may be dry, move the arm up and down a few times and the system will refill.

Eco

That is what I found when I had a similar problem

 

[rebecca14]

I also suggest to power flush your system. But before doing that, try to go to a plumbing consultant and ask if what are the advantages and disadvantages of power flushing in plumbing.