Could your boiler’s diverter valve be faulty?
In this article, we’re going to explain what a diverter valve is, how it works, and what the signs are when it is not working correctly, along with possible solutions.
What is a diverter valve?
Your combi boiler diverter valve is a valve that opens and closes to provide heat to the radiators or to heat your water.
The diverter valve will always give priority to your hot water, so if you turn your heating on, and then a hot tap, it will heat the water to the tap first.
How to diagnose a faulty diverter valve
If when you turn on your tap and find you are not getting hot water, it may be because the valve is jammed and not working properly.
Another sure-fire sign is having to turn on the heating in order to get hot water to come through the tap. This means the valve is jammed open in the heating mode.
If you are getting all the hot water you need, but no heating, first check all your time clocks and controls are working. If everything else is fine, it’s almost definitely the case that the valve is not opening for the heating.
What should I do now?
Now that you’ve diagnosed the problem, you should call out a gas safe registered engineer to come and replace the diverter valve or service the working parts of the valve.
On a boiler under eight years old, this should be a routine fix and should not take any longer than an hour, as parts should be readily available.
However, a combi boiler over eight years old may be harder to source parts for and this is also a sign that other parts of your boiler could be wearing out.
How much will it cost?
A combi boiler diverter valve should cost between £100 – £150, plus the cost for labour and time. Taking that into account, it should cost you around £250 to get your faulty diverter repaired. It should also come with a parts and labour guarantee for between 3 – 12 months, although this could depend on the age of your boiler, as some parts may be close to breaking down.
If you are on a service plan this would cover the cost, however if your boiler is old and you need replacement parts quite often, it may be wise to consider replacing it.
A replacement boiler would be more cost effective over time, and because warranties last up to eight years, you may not even need a service plan. You’d also notice the difference on your monthly heating bills.
Conclusion
If you aren’t sure whether your diverter valve is working properly, it’s fairly easily to diagnose the problem. Tell-tale signs include having to turn on the heating to get hot water, or having plenty of hot water but no heating.
Your diverter valve should cost around £250 to repair with a gas safe registered engineer.
However, if your boiler is old and frequently experiencing problems, you may want to consider a replacement which could save you money in the long run.
Are you having problems with your old combi boiler and thinking of investing in a new one?
Getting hot water and heating warm aswell the problem I get is that when the water alone is on there is quite a loud vibrating sound coming from the tank but when the heating is on by itself or with the water at the same time there is no sound I know this because when they are both on there’s no sound but when the temperature on the heating dial is reached and the heating automatically goes of tand that leaves the water on by it self the vibrating sounds but I not experiencing the faults that you mention regards not getting heating or hot water
Getting hot water and heating warm aswell the problem I get is that when the water alone is on there is quite a loud vibrating sound coming from the tank but when the heating is on by itself or with the water at the same time there is no sound I know this because when they are both on there’s no sound but when the temperature on the heating dial is reached and the heating automatically goes of tand that leaves the water on by it self the vibrating sounds but I not experiencing the faults that you mention regards not getting heating or hot water
Hello I am only getting central heating working with my Baxi Maxflow Combi WM.
I was told it is probably the diverter valve and that I should get new boiler. I found such a valve to order. Do you think I should order it, because I need to sort out the problem as soon as possible. Is is likely to be some other issue. Thank you very much for your help! Kind regards, Yoko Wada
The above is really useful, however could the diverter valve also be faulty in the following situation. Heating works fine. Hot water works fine, but when you turn on a cold tap to reduce the heat, the hot water switches off?? I have a Worcester Combi CDi28.
I have recently replaced the diverter valve . The imfault light would flash on 60 degrees indicating pump or pressure. It still flashed occasionally but the engineer said the main circuit board was sending faulty signals as well . Lesson is if it’s the valve ,it’s usually just a worn diaphragm. Replace these first x1 for heating x 1 for domestic i.e. the shower. A random fault is usually the circuit board . My boiler is a baxi combi e. Hope this helps ?
When I switch the heating on constant sometimes it won’t come on
Hi, I’ve just had my worcester bosch boiler diverter valve replaced, as the heating was working but the hot water was not. The boiler is about twenty years old, however the whole thing has stopped working 9 days after it was fixed so now we have no heat or hot water. You mention that the parts should be guaranteed , so I wonder if that should be the case for me, even with such an old boiler ?
i turn the heating on.works fine.then the hot tap/on works fine ,but when i turn hot water offthis shuts down the heating,untill i reset the boiler
we have scalding hot water and no heating then if we run off some hot water the heating sometimes comes on. Would this be a value problem?
Heating is working fine get hot water in kitchen, cloakroom and wash basin in the bathroom but not even tepid in the bath. Its a Worcester. 6 yrs old.
Our boiler will not fire up on the water side unless the taps are turned fully on. There is plenty of water pressure. Is this likely to be a diverter problem or a flow switch?? Help much appreciated.
I have a Procombe 100 He boiler, which was fitted in 2008 there have been no issues with the boiler since it was fitted until now.
The hot water keeps running hottish (cooler than usual) for about 1 minute then cold for about 1 minute then goes hot again and so on. When the water goes cold the boiler light is flashing. when its running hotter the boiler light is constant.
The heating seems to be working fine. Although I have not tried keeping the heating on and running the hot water at the same time.
The problem seems to have become worse since Water meters were fitted on the outside mains, but this may be a coincidence, as we have always had to adjust the tap to certain level to run a hot bath. But nothing currently seems to be keeping the water temperature constant.
time. I must admit it is well over due for a service which I am going to arrange at the same time as getting the problem repaired. Hoping to keep costs down as much as possible by having an idea of what the problem may be.
Thank you.
following on from my e mail above. I just tried running a bath with the heating on and still runs cold after about 1 minute, although seemed to be running a bit hotter before going cold.
I have a leak from my ravenheat rsf84et where the micro switch joins the diverter. Not sure if it just needs the diaphragm replacing although no engineer seems to want to do this. The diverter is only 1 year old
The hot water works but not hot enough, to get any decent temperature on hot water I have to reduce the volume of water flowing through the tap. I am a Gas Safe registered contractor but not too familiar with the Baxi Combi range.
no hot water can hear ticking sound like clock ticking louder all other radiators are o k whats problem ?
Hi can some one advise please we have been told we need a new diverter valve for the combi boiler and they say it would be £480 altogether basically we have a leak that’s appeared under the wahing machine that we can’t seem to access due to the floor expanding and wedge Inot nit sure if it’s the pipes behind or the washing machine…then I was lookingat the boiler amd every so often a drip appears at the bottom of tank so the Plumber said it could be two separate things going on. Great timing but is it right it would cost that much?
Hi. We have hot water but no central heating hardly. Luke warm rads upstairs but nothing downstairs. Boiler bout 10 yr old.baxi. bled rads everywhere. Reset boiler.sometimes luke warm rads downstairs.but then days later cold as.
My boiler made a clicking sound yesterday and after that the heating started to go down. Now, the heating don’t work at all but the hot water works fine. Is it a broken valve? or can it be something I can fix immediately myself? I only rent the apartment and my landlord don’t pick up his phone, and it’s freezing in here. Thankful for any help!
I have a Sime Format 80, the heating and hot water run for 20 min with the hot water not exactly scalding, but hot. Then the heating goes off (room at temp) but when hot water is required or the heating is required to come on again the boiler will not reignite.
Would this be a divertor problem?
Hi I have a Biasi Combi Boiler – River Plus HE (M296 24SM/C)
Everything seemed fine yesterday but this morning I have no HW.
Central heating works fine and boiler fires up for this.
But No HW on direct HW or when the heating is on.
When on HW only the boiler does not fire up. It only fires up when I put on the heating.
I’ve turned off the main power source and turned back on but problem still the same. Pressure is fine between 1.5 and 2 bar.
There is a very slight change in water temp from icy cold to barely luke warm at first then icy cold, barely noticeable but a change in temp non the less – could this be the diaphram?
My other thoughts are that it could be the Diverter Valve or possibly a faulty Flow Sensor or faulty Thermal Sensor?
Any other thoughts please and are the sensors any easy fix or expensive to replace?
Thank you for any help.
My shower gives me hot water then goes cold, then hot again. Is this the diverted valve. ..,? .
My red light is on my boiler even if I turn it off or reset it. Getting no hot water at all. Any idea what the issue could be?
I have no hot water ,checked boiler it was flashing L F reset boiler seemed to come on .now showing d on combined boiler
Have done already
The heating upstairs comes on when i have a shower.
What do u think is the problem ?