Three port valve issue??

[plums12001]

Hi,

I have a gravity fed heating system with a valiant boiler. It's a system with a hot water tank in the cupboard and a couple of tanks in the loft.

Basically the problem I'm having is....... When the programmer turns on to boil up the hot water tank it seems to be turning on my heating even though my thermostat isn't calling for heat. I suspected it was the three port valve so I changed the electronic controller on the top but kept the old valve in place as it was the type you could unscrew and change the head.

Also some further information..... When the thermostat isn't calling for heat and the programmer for the water is off, my pump seems to circulate water around the heating system and never turn off until it's turned off at the programmer.

My questions are....

Does it sound like a three port valve issue?

If it is the valve then is a full system drain required in order to take it off and replace it with a new one?

Thanks in advance for any advice 👍

 

[Deleted member 120897]

Is the pump in with the boiler or separate? How old is the boiler and how old is the issue? Could be the 24v link at the boiler has been left in.

 

[king of pipes]

It would be the most likely cause but theres other causes a blocked cold feed and or vent , a faulty programmer , thermostat , a failing or failed pump , debris in the 3 way valve body , the heated system water can creep down the return pipework it needs diagnosing , also check the wiring even a loose wire connection can cause it ? . Changing a valve body will require draining not completely but to a manageable level ? it maybe a good time for a system clean and flush adding new inhibitor it can and will help in the transfer of heat for winter. .Regards kop

 

[plums12001]

Is the pump in with the boiler or separate? How old is the boiler and how old is the issue? Could be the 24v link at the boiler has been left in.

Hi, the pump is in the airing cupboard with the hot water cylinder. The boiler is about 5 years old and serviced regularly. I've had the issue for a long time, engineers have been before on several occasions and they seem to fix it temporarily but then it comes back. They have never really explained what they found, they usually say something like.... Oh it was a wiring issue or something like that but when I press for more details they don't usually give it. If you need anymore information just ask. Thank you for your reply

 

[plums12001]

It would be the most likely cause but theres other causes a blocked cold feed and or vent , a faulty programmer , thermostat , a failing or failed pump , debris in the 3 way valve body , the heated system water can creep down the return pipework it needs diagnosing , also check the wiring even a loose wire connection can cause it ? . Changing a valve body will require draining not completely but to a manageable level ? it maybe a good time for a system clean and flush adding new inhibitor it can and will help in the transfer of heat for winter. .Regards kop

Hi, thanks for the reply. Funny you should mention the debris issue, I'm currently changing the rad in the hallway and when I disconnected the feeds, the inlet was just dripping out black gunk and water. I have a 5 meter long drain unblocker that fit up the 10mm pipe and managed to fill a washing up bowl full of black dirty water but I think the blockage is still a bit further up the pipe but I couldn't go any further because I hit a bend/joint in the pipe. Even with all the gunk coming out it's still only dropping. All the other radiators seem to be functioning well and I've just removed them one by one and flushed them all out.

I have a tank bung kit and can drain the cylinder no problem if I need to change it. I was wondering though.... The pipe that comes up in to the 3 port valve from the boiler... Will water come out of this when the valve is removed? I'm guessing if it's all turned off and isolated then it won't but not 100% sure.

Yes I was looking at the flush option, how much would I be looking at roughly for that? I don't want to get ripped off so a ballpark figure would be handy to know. I'm in a 4 bed with 11 radiators.

Thanks for your help 👍

 

[king of pipes]

It varies depending where you are in the country £300 - £500 is not uncommon continuing wiring issues is a consern and needs addressing. Kop

 

[plums12001]

Thanks for the replies, turns out it was a dodgy thermostat in the hallway. Replaced it and now it's all working fine as it should 👍