Ye olde central heating question -ALPHA boiler & 3 way v

[foggys916]

Hi,

Had a new ALPHA condensing boiler fitted earlier this year following the demise of an old Potterton we had. This is a traditional system with a hot water tank gravity fed from a tank in the loft.

All seemed to be fine, until the start of the summer. I noticed that the radiators in the bathroom and hall (either side of the same wall) were warm/hot, even though the central heating, via the room stat was effectively off (i.e. set to below the current room temperature). The installer, who is CORGI, said that this was normal as the boiler need to; “output into the radiators to keep the heat exchanger working??” (I could be wrong here).

I accepted this but noticed two further things.

Firstly, the old mechanical timer had stopped working, this is now replaced.

The three way valve (Honeywell) never seemed to move, i.e. the lever that sticks out the side never moves through all manner of combinations of HW & CH. I replaced the head unit…..it still doesn’t move.

I also had rad-stats fitted to all but the bathroom and hall radiators.

So currently I find this;

With just the hot water on (via timer/controller), the central heating pump seems to always be on. All the rads will therefore get hot to the temp they are set to (remembering the central heating, via the timer controller is OFF). The three way valve never seems to move, CH pump always seems to be on. I have not attempted to manually move the 3 way valve itself (where the head unit has been removed).

So the question is;

1) Is there a fault with the boiler

Or

2) Is the three way valve (i.e. the valve itself, not the head unit) jammed.

Or

3) Something else.

I haven’t asked the installer back just yet, mainly as his wife has just had a child and I know there has been complications, but I’d rather he had a look once I can be clear in my mind what the fault is.

Anything you experts could offer would be great.

Steve

 

[gas4you]

In normal use you will not visibly see the lever on the zone valve move. You will however be able to feel if it is 'loose' in a certain position. If it is loose and can be moved completely over away from rest it will be on for ch only, if over to the rest position it will be set for HW, mid way both.

Your rads should not get warm with a modern system when just HW is selected. You either have a sticking valve body or somewhere a return backfeed in the pipe work so the warm return water from the HW cylinder is finding its way into the rads. This could need pipe work arrangements changing if proved to be this.

Call your installer back and ask him to put it right.

 

[foggys916]

gas4you.

In the past I have seen the lever on the valve move (albeit slowly), though this was with the old Potterton.

The lever is 'loose' i.e. can be moved from one side to the other, I don't feel the resistance that would be there sometimes.

Steve

 

[gas4you]

In that case it has operated and is open in one position.

The two things that concern me about your new instalation are that you appear to be left originally with the 'old mechanical timer' and the comments your installer has said about the rads getting warm so th boiler can keep its heat exchanger warm.

This statement is absolutely hogwash on a modern up to date boiler and ch system, also totally against energy efficiency regs.

One has to wonder if the chap really was registered

 

[foggys916]

Dave,

No he is registered, but only recently got his qualifications for this. Prior to that he did standard plumbing work.

I have changed the valve head unit, once before, I think I'll take it off, see if the spring returns the unit to the CH off position and see if this is off.

Interesting what you say about the heat exchanger/rad statement, don't know if I got this right, but don't CH systems need to be able to output some stuff to a rad? This was why (I was told) that rad stats were not put on all rads (i.e. left off the hall and bathroom rad).

Steve

 

[foggys916]

..see if this TURNS THE PUMP OFF