H/L reset light on a warmflow boiler

[chicken5812]

Hi just wondered if anyone can help me. I have a warmflow boiler and it fires up then the pressure rises to 1 then it cuts out and the H/l reset light comes on. Pressed the reset button, left it to cool, turned it off and on but nothing seems to work. Any info will be great thanks.

 

[dontknowitall]

Has your (central heating) pump failed?

 

[Best]

You have to let the boiler cool sufficiently, before you can reset the high limit stat. Your control stat may be faulty.

 

[Roger Welton]

If the high limit wont reset after the boiler has cooled, then it will require replacement in addition to further investigation as to the cause of the overheat.

I take it you aren't pressing the burner reset and have found the hi limit stat (on or under the control panel)

 

[chicken5812]

Hi just wondered if anyone can help me. I have a warmflow boiler and it fires up then the pressure rises to 1 then it cuts out and the H/l reset light comes on. Pressed the reset button, left it to cool, turned it off and on but nothing seems to work. Any info will be great thanks.

Hi thanks for your advice, I've let the system cool and it fired up ok but then hit 1 on the pressure and the light came back on. This time as it was heating up I took it off heating water and put it on to central heating but nothing happened, does this mean the central heating pump has packed up. Also when it was on heating water the water came red hot for a few seconds then went cold. The vent on top of the boiler also hisses sometimes, if this has any significance. I'd be grateful for any information. Thanks.

 

[dontknowitall]

I'm still thinking pump is worth an investigation.

There are two pipes at the pump - one in and one out. Both should be equal temperature and the pump should vibrate when you put your hand on it.

On the pump there is an arrow indented into its design which shows the way the water flows through it. The pipe entering the pump will be hot. If the pump's not working properly the exit pipe will be colder.

 

[chicken5812]

Hi thanks for the advice.Yes pipe is hot going in and cool coming out. How hard is it to replace the pump? can see how to take it off, how do you turn the water off to the boiler and is there anything in particular I would need to know, Thanks.

 

[dontknowitall]

Sharp intake of breath ... scratch chin ... ooo, you wouldn't want to start from here ... who on earth did that? ...


1. Turn off heating (ie the electrical supply to it)
2. Just above and below pump are the gate valves, which need to be turned off.
3. Remove wires from pump.
3. Have towel ready and unscrew pump from gate valves then remove pump.
4. Put new pump on (correct way round) and wire it up.
5. Open gate valves
(6. Phone for plumber when it goes wrong?)

 

[chicken5812]

Thanks, any ideas on places for best priced pumps. Also there are two pumps they look like they are joined together, they look like they will seperate will one go to heating one to water, is it just the water one that will need replacing or both. Thanks.

 

[dontknowitall]

I'd pop into your local merchant for prices.

It's unlikely that both pumps have failed. If one has failed then worth changing it. If both have hot pipe one side and cold the other then it's more likely to be something else.

 

[chicken5812]

There is one hot pipe coming into them both and both pipes out are cool. What else do you think it could be. Thanks.

 

[chicken5812]

Thanks, one pipe going in to them both is hot both pipes coming out are cool. what else do you think it could be? Thanks.

 

[dontknowitall]

Quite possibly the thermostat on the boiler as mentioned at the beginning. Perhaps a wire in the wiring centre? Perhaps a zone valve (depending on how it's wired and affecting the other zone valve)?

Could be one of a number of things. Sounds electrical in some way though, unless it's the expansion vessel.

 

[chicken5812]

Thanks, sounds to complicated for me, guess i'm going to have to bite the bullet and get a plumber.Thanks again for your help.

 

[SimonG]

What's the pressure gauge read when cold?

 

[Millsy 82]

What pump is it? does it have a name on the front? Are the pumps joined together water comes in pipe comes out the side of the first then joined to second then pipe out as it might still be a pump problem.

Also have you carried out any work on the system ie removed rad as you might have an airlock in the system.

 

[chicken5812]

when its cold the pressure gauge is zero

 

[chicken5812]

Grundfos pump and yes they are joined together. I've recently bled the radiators, I think it could be an airlock but don't know how to bleed the boiler, can you let me know?

 

[dontknowitall]

Have you tried filling the system with water until the gauge reads about 0.7? Normally, the gauge should read around 1.1bar or so (and hold there during firing).

 

[dontknowitall]

Bleedin' boilers ...

Somewhere will be a filling loop which is a length of braided pipe around 1 foot long or so. At the end of it there will be a black plastic piece which you turn 1/4 turn, like a tap.

 

[SimonG]

As DKIA says, top it up then run it and watch the pressure gauge. I would imagine that it will hit 3 bar and dump water out of the pressure relief. I'd be looking at the charge in the expansion vessel or the hose to the vessel.

 

[Best]

As others have already said, have the expansion vessel air charge checked & pumped up first & the systems water charge. Those Warmflow Combis from about 2010 onwards have a pressure switch which cuts the boiler off when system pressure hasn't been kept above 0.3 bar. Yours may be older model. Be careful of the stats, - there are 3 of them, - control stat, high limit stat ( manually resettable only I think ) & another lower limit stat that is automatically reset I think. I have seen these fail & boiler overheating. Check the pumps are working by holding front of them. The pump for the radiators will only start after the hot water end is satisfied.