Blocked Manifold?

[endaxi]

Here's an update...

For many years we've had the hot water set to 'all day', so from early morning until late at night. That means any time the heating is on the hot water is too.

Today I turned the cylinder coil valve from fully open (5 turns) to half way and switched the hot water to off for good measure.

With TRVs set to our normal operating mode (some fully open, some fully closed and the rest somewhere in-between) every downstairs radiator got hot. At last.

Now....... having read-up on Honeywell valves it seems that if all is well they should only open and let water through the coil when the hot water is switched to ON and there is a demand from the cylinder thermostat. The Honeywell in turn then switches on the boiler and pump. If this is the case then the hot water should only have an effect on the heating when the cylinder thermostat is calling for heat.

I remember about 10 years ago a BG engineer said the wiring in the airing cupboard was wrong and he had put it right.

I'm now wondering if he put something wrong that was previously right.

I checked the Honeywell and it was indeed closed (lever would only move a bit up the slot). I've switched the hot water on and the valve is now open (lever moves all the way in the slot). This is normal so far as the cylinder is calling for heat and the pump and boiler are on.

I'm going to wait until the boiler and pump switch off and make sure the valve is closed again. I'm sure it will be as it's the Honeywell that switches the boiler and pump on and off if I've read things right.

Ok... the boiler and pump are off and the Honeywell is closed (if I go by the fact the lever only manually moves a third of the way up the slot). If I turn the heating on the coil Honeywell stays closed so all ok there then.

If the Honeywell valve is working ok then water will only flow through the coil occasionally to top-up the water temp so I'm wondering if having the HW to on all day and the manual valve to the coil fully open as it was should affect the heating that much. The only other thing could be the valve not seating properly when it closes, thereby allowing some hot water through the coil all the time (like another by-pass).

Anyway, I'll leave the manual valve as it is and set the HW to only come on for a couple of hours in the morning and evening and try the heating from a cold start tomorrow with the TRVs set to normal conditions and see how things feel.

It's interesting stuff this and I'm learning a lot so thanks for all your inputs. Things are definitely looking up here.

Cheers for now.

 

[Terrywookfit]

A sketch of the layout with rough dimensions would be good. Sounds like bad design.
Has it ever worked properly.

 

[endaxi]

A sketch of the layout with rough dimensions would be good. Sounds like bad design.
Has it ever worked properly.

My wife thinks it used to be better years ago but I'm not so sure. You'll see my latest update above. We posted about the same time.

 

[Terrywookfit]

Do you have a 3 port valve or 2, 2 ports.
Is there a balancing valve on primary coil loop.

 

[endaxi]

Do you have a 3 port valve or 2, 2 ports.
Is there a balancing valve on primary coil loop.

Sorry Terry I'm not a plumber or heating engineer (as you've probably guessed) but as far as I can see it's two 2 ports. A metal Honeywell for HW and a grey plastic one for CH. One pipe in and one pipe out of each.

I don't know what a balancing valve on primary coil loop is.

I'll be off-line for the rest of the day but will respond tomorrow to any more advice or questions.

Thanks

 

[Doggit]

I suspect part of the problem of the downstairs rads getting hot slowly, may be down to the heat getting lost in the walls first, so once the walls are warmed, then you'll get hot water into the rads. But if the rads that are furthest from the boiler take the longer to heat up, then you need to open these up more than the closer ones, as there's more flow resistance the further the water has to travel.

Now you're relying on the TRVs for your balancing excercise, but that could be causing a red herring. Whilst you're trying to sort out how to get the system set up, you'd be better off having the TRVs set fully open, and then adjust them after everything works the way you want it to. I'm not convinced that TRVs work the way that they are supposed to, but they should deal with say how the sun will warm a room, and then it'll cool down later as the sun moves round. If there was no TRV, then the rad would be putting out the same amount of heat during the day, no matter what the external situation was.

 

[endaxi]

I suspect part of the problem of the downstairs rads getting hot slowly, may be down to the heat getting lost in the walls first, so once the walls are warmed, then you'll get hot water into the rads. But if the rads that are furthest from the boiler take the longer to heat up, then you need to open these up more than the closer ones, as there's more flow resistance the further the water has to travel.

Now you're relying on the TRVs for your balancing excercise, but that could be causing a red herring. Whilst you're trying to sort out how to get the system set up, you'd be better off having the TRVs set fully open, and then adjust them after everything works the way you want it to. I'm not convinced that TRVs work the way that they are supposed to, but they should deal with say how the sun will warm a room, and then it'll cool down later as the sun moves round. If there was no TRV, then the rad would be putting out the same amount of heat during the day, no matter what the external situation was.

I agree with what you say, Doggit. The furthest rads from both the boiler and the pump are also the biggest rads so they will definitely take longer to heat-up. I have the lockshields fully open on these. With the lockshields on the hottest rads at around 1/4 turn I was starting to think there wasn't much to be gained from closing them further. I'm happy to keep at it if you think there's a possibility of me getting all rads upstairs and down hot at the same time.

Is there a best method for balancing rads fed from small bore pipes off manifolds or is it just continue with nipping down the hot ones and opening up the cooler ones? Is it normal to have some at 1/8 turn as long as they still heat-up?

 

[dilalio]

You can just crack open the lockshields on the hot rads... as long as they stay hot! Water will take the path of least resistance and this 'should' be the rads that 'aren't' getting hot if their valves are wide open... if instead it takes the 'bypass' route then the resistance to the furthest rads is too great. Keep at it and remember that even the TRVs will close down to a tiny bore and still allow water to pass so lockshields can do the same!

 

[Nige F]

Is there a best method for balancing rads fed from small bore pipes off manifolds or is it just continue with nipping down the hot ones and opening up the cooler ones? Is it normal to have some at 1/8 turn as long as they still heat-up?

1/8 is fine - just continue nipping down- it's time consuming but your time is free

 

[Doggit]

s there a best method for balancing rads fed from small bore pipes off manifolds or is it just continue with nipping down the hot ones and opening up the cooler ones? Is it normal to have some at 1/8 turn as long as they still heat-up?

You've got it Endaxi, just keep working at it to fine tune it. I'm sure you could find someone to take out the by pass valves quite cheaply to eliminate that possibility. But you shouldn't have to be working this hard at things, so has the boiler been sized on the assumption of 15mm pipes everywhere. Does it need a stronger pump to be fitted to get the water to the furthest point, or is the pipe run long enough that you need a secondary pump bu the manifold to give it a bit more ooomph. Or is the boiler up at it's limits, and you need a bigger one.

 

[endaxi]

The latest state of play...........

Firstly, thanks for the latest advice and encouragement which has given me the confidence to give those lockshields a good seeing-to.

I started with Heating and Hot Water both OFF. All rads stone cold at the start and I ran a bath to put some demand on the water.

Armed with my spanner I closed the best half of the upstairs radiators' lockshields to 1/8 and the other half to 1/4. I also adjusted some of the downstairs ones according to how they've been performing.

With all TRVs fully open I switched on the heating and all rads started to warm up. After 30 minutes when all rads were hot bar a few (which were fairly hot) I made some slight adjustments and did the same after another 30 minutes. I then left things alone for an hour.

I now have every single radiator hot at the same time for the first time ever I think.

I then switched the hot water on and checked that the cylinder coil Honeywell valve opened. All ok there.

I monitored the rads and they all stayed hot whilst the water was heating. The cylinder valve closed itself off after 50 minutes by which time all radiators were still hot, although the very worst one historically had lost a bit of heat (it was still quite hot though).

Ten minutes after the cylinder valve closed all radiators were hot again....... even the very worst one.

Tomorrow I will adjust nothing and just switch the Heating and Water on from cold and have all the TRVs open. If all the radiators (and the hot water) get hot in a reasonable amount of time I'll be a very happy bunny.

Just a quick question.... Our hot water has always been VERY HOT. How can I reduce the temperature a bit should I want to? The tank is a Megaflow and the only thermostat I can see is the one in the immersion heater compartment. Mind you, our new boiler also has a thermostat. That would probably affect the heating temp as well though I guess.

Thanks again for all the help.

 

[Doggit]

There should be a thermostat on the tank, and one in the house as well, otherwise the system will work from the temperature of the boiler stat (or is it a room stat), and that's not as efficient.

Well done for balancing the system, but the last rad getting a bit cooler whilst the how waters being heated, shows the boilers running at it's limit, so it'll be interesing to see how it copes in the dead of winter.

You could see if there's any ability to reduce the flow of water into the tank. This would obviously take the tank longer to heat up, but might help the last rad to stay hot.

 

[endaxi]

There should be a thermostat on the tank, and one in the house as well, otherwise the system will work from the temperature of the boiler stat (or is it a room stat), and that's not as efficient.

Well done for balancing the system, but the last rad getting a bit cooler whilst the how waters being heated, shows the boilers running at it's limit, so it'll be interesing to see how it copes in the dead of winter.

You could see if there's any ability to reduce the flow of water into the tank. This would obviously take the tank longer to heat up, but might help the last rad to stay hot.

I had a new immersion thermostat fitted a few months back and asked the guy if there was one to control the water temp when the immersion wasn't in use (we only use the immersion when the boiler breaks). He couldn't find one and neither can I. Not to worry, that's a minor problem.

As regards restricting the flow into the cylinder coil, I screwed down the valve half way on Tuesday (see my update at the top of this page). I suppose I could turn it a bit more if needs be but at the minute it's not much of an issue if one rad cools down a bit when the tank's heating. It's the smaller of the two rads in the lounge so the bigger one stays hot. We'll see what happens in the winter. I think I've got the measure of the system now so can tweak things if I think I need to.

Let's see if everything works ok from scratch tomorrow.

 

[Doggit]

So you need the bypass valves sorted out, and a room stat and a tank stat installed, and not having them, would suggest there isn't a 3 port valve in the system either, so you've still got a lot to do, but you're essentially set for winter, so best of luck. Come back in the spring, and give us an update then.

 

[endaxi]

So you need the bypass valves sorted out, and a room stat and a tank stat installed, and not having them, would suggest there isn't a 3 port valve in the system either, so you've still got a lot to do, but you're essentially set for winter, so best of luck. Come back in the spring, and give us an update then.

Just fired-up the heating from cold and all rads started warming within a few minutes. They all got hot soon enough with the last one progressively getting to fully hot after about half an hour. I'm happy with that... and so is my wife.

By the looks of it I've got two 2-port valves, one for CH and one for HW. I have a room stat in the hall to control the CH temp. It's just the HW that I can't seem to regulate. I'll drop the boiler stat down a bit and I can always put it back up if I need to when the weather gets colder and we need the heating.

I'm very happy with how things are now so will let sleeping dogs lie, I think. The most I'd probably do now is look into a tank stat if I feel the need.

Many thanks Doggit for doggedly sticking with me and thanks too of course to all who contributed to the thread with ideas and advice.

I'll report back in the spring.

Cheers all.