old programmer display and radiator with trv

[zoethorne]

hello there all

i am a keen diy'er and have taken on many jobs over the years around my homes

i have a couple of things i am not 100% sure off and would like some advice from anyone who many have come across similar situations in their past.

first of all: i have a heating and hot water programmer on my kitchen wall. it is Drayton. Tempus-7

It is chunky and fairly old, i'd say over 15 years old. the problem is, the digital display is fading badly, and is hard to read. i might buy a new programmer and have seen in shops similar programmers but more modern design and look. also a more modern tempus 7 is available.

is the digital display likely to be all that is wrong or will other things go wrong too - and also, if the programmer is battery operated (which i believe mine is) - is all that is required a battery change or more than that?

my second point is: i want to flush out a radiator as it has sludge in it i believe (it required venting a lot and also when bleeding it it has a lot of black water escaping). - the radiator in general has a TRV , but I have heard that these cannot be changed without a trv cap as water will not shut off fully. how do i overcome this problem?

thanks for hearing and reading through my long story!

 

[D_Hailsham]

... if the programmer is battery operated (which i believe mine is) - is all that is required a battery change or more than that?

The Tempus 7 is mains powered; it has a permanent battery as a backup in case of power cuts.

If it is fading the probability is that the LCD display is on the way out.

I want to flush out a radiator as it has sludge in it i believe (it required venting a lot and also when bleeding it it has a lot of black water escaping).

Does the rad feel roughly the same temperature all over or is there a noticeable cold area at the bottom? If so, this is the sign of a sludged up radiator.

the radiator in general has a TRV , but I have heard that these cannot be changed without a trv cap as water will not shut off fully.

It all depends on the Make and Model of TRV. Some only close down to a Frost position, others close completely. Which TRV do you have?

 

[zoethorne]

Hi there D_Hailsham

The programmer has a square battery I know for a fact which is removable. The new programmers I was looking at in a shop didn't seem to be as wide and didn't require a battery - so does this mean they are not as good and will fail in a power cut and need to be re-set manually? also the new look Tempus 7 also looks slimmer and I didn't require a square 9v battery.

The radiator feels warmish at the bottom but a lot cooler/colder at the top. I have bled it probably every week or two and the problem keeps coming back. I presume it is sludge as the black water when venting that comes from the top of it after the air has all escaped, and also that all my other radiators, (I have 6) are all fine.

The TRV is Drayton. Also, quite old, about 15 years I think. They have frost setting yes. So will probably not close off fully?

 

[D_Hailsham]

The programmer has a square battery I know for a fact which is removable. The new programmers I was looking at in a shop didn't seem to be as wide and didn't require a battery - so does this mean they are not as good and will fail in a power cut and need to be re-set manually? also the new look Tempus 7 also looks slimmer and I didn't require a square 9v battery.

I was referring to the latest Tempus 7. Sounds as if they are now using permanent batteries (possibly rechargeable) instead of the user replaceable 9v types. Why not try a new battery?

The radiator feels warmish at the bottom but a lot cooler/colder at the top. I have bled it probably every week or two and the problem keeps coming back. I presume it is sludge as the black water when venting that comes from the top of it after the air has all escaped, and also that all my other radiators, (I have 6) are all fine.

Cold at the top is a sure sign of air. There could be a small amount of sludge at the bottom. Are you turning the boiler off and allowing the water to cool down before bleeding the rads?

The TRV is Drayton. Also, quite old, about 15 years I think. They have frost setting yes. So will probably not close off fully?

Does it look like the TRV4? If so you can get a "decorators cap" which will shut the valve completely. Try you local plumbers merchant (not a DIY shed) or failing that Phone/Email Invenys/Drayton 0845 130 5522 or [email protected].
I found them very helpful; they will probably send you some for free.

 

[zoethorne]

Shall try a new battery now! Thanks.

About the rads, I bled them both hot and cold, but what difference would bleeding them cold do?

How is air getting in?? it is only that rad? maybe the radiator nut is not 100% tight enough possibly? Someone told me that sludge/sclae build up causes air (nitrogen) as a by-productin the radiator. Is this true?

Also I have heard about a penny trick to close off the pressure pin on trvs? is this a good idea? how do i do it correcty?!

 

[D_Hailsham]

About the rads, I bled them both hot and cold, but what difference would bleeding them cold do?

1. You can't bleed a rad if the pump is running - otherwise water will be forced out of the bleed valve - all you want is for the air to escape naturally.
2. Allowing the water to cool reduces the amount of air trapped in the system

How is air getting in?? it is only that rad? maybe the radiator nut is not 100% tight enough possibly?

Possible or a leaking valve spindle on the lockshield valve.

Someone told me that sludge/sclae build up causes air (nitrogen) as a by-product in the radiator. Is this true?

No it's hydrogen which is produced by the interaction between the water and the steel radiators. This produces rust and hydrogen - which also comes out of the bleed valve.

Do you have any inhibitor in your system? If you don't know, it would be worth flushing your system with Sentinel X400 for a few weeks then adding X100 inhibitor and X200 if you are in a hard water area.

Drain system completely and flush through with cold water until it comes out clean(ish).
Refill, adding X400 at the same time.
Run for two or three weeks
Drain and flush with cold water
Refill, adding X100 (and X200).

If you want to be really clever, shut down all radiators and let water circulate just through the main pipes for say 10 minutes. Then open one rad fully (both valves) and do the same. Close that rad and do the next. The idea is to give each rad, in turn, the full flow of water, which will help dislodge the sediment. If you have a hot water cylinder, treat it as a radiator.

It's a DIY flush without spending £300-800 on a power flush!

Also I have heard about a penny trick to close off the pressure pin on trvs? is this a good idea? how do i do it correctly?!

Yes. that is one option. Turn TRV to max and remove the head.Find a coin or something similar which will fit inside the head. The idea is that this will then press on the pin sticking out of the valve body. Gently replace the head with the coin inside. Then close the TRV slowly until it stops (depending on how thick the coin is the TRV may only go down to 2 or 3); this will be the fully closed position. Don't force the TRV.