Installing Controls

HappyHarry

I'm looking for some help installing new controls for a small 3 bed house.
I want to separate the HW and CH.

Current setup is gas boiler, 24 hour analogue timer, thermostat and a manual summer valve in the hot-press.

The electrical side isn't a problem. I will be adding a thermostat to the cylinder and new control panel with dual 7day timers.

On the plumbing side, can I just put motorised valves where the summer valve is and another on the inlet to the Cylinder? It seems too easy?

Under what circumstances is a bypass valve required, where should it(they) be put?
How come it's not required in the current system when using the summer valve?

BTW the pump was removed from the hotpress by the previous owners, I presume when the boiler was replaced, I guess the pump is in the boiler now?


Thanks.

HappyHarry

Anyone?

Outkast_IRE

Ok i will chip in with this.

Ok you have what your calling a "summer valve " this is cutting off the heating from the boiler for the summer and leaving only the cylinder being heated correct?

The bypass valve isnt required in your current system as if theres no motorised valves then there should always be somewhere for the pump to pump to. ( In general i know its possible to turn off every rad and the summer valve etc but this doesnt happen in reality).When you install 2 motorised valves on the system this will no longer be the case and you will need a bypass.

Without looking the the job , with your vague description it does sound like you could replace the summer valve with a motorised valve, and put a motorised valve near the cylinder , make sure you put the bypass before the motorised valve on the cylinder otherwise it obviously wont work correctly.


With newer gas boilers the pump is often built into the unit.

Just an ad lib , i hope you know what your doing if its as simple as it sounds there would only be a few hours work on the plumbing side for a good plumber plus time to drain down and refill . If your not sure what your doing reconsider doing it yourself, i have seen some nasty work over the years from DIYers.

spireland32

Get a plumber or rgi recommend to you by someone else. It's not guess work or a diy job

HappyHarry

Outkast_IRE wrote: »

Ok you have what your calling a "summer valve " this is cutting off the heating from the boiler for the summer and leaving only the rads being heated correct?

Almost, it' only the cylinder being heated with this valve closed but I think that's what you mean. It's so I can have hot water (without the immersion) in the summer without heating the house.

Outkast_IRE wrote: »

The bypass valve isnt required in your current system as if theres no motorised valves then there should always be somewhere for the pump to pump to. ( In general i know its possible to turn off every rad and the summer valve etc but this doesnt happen in reality).When you install 2 motorised valves on the system this will no longer be the case and you will need a bypass.

So the bypass is to cater for the situation where both motorised values are closed and the pump is running for some reason, e.g. frost protection or heat dissipation?

Outkast_IRE wrote: »

Without looking the the job , with your vague description it does sound like you could replace the summer valve with a motorised valve, and put a motorised valve near the cylinder , make sure you put the bypass before the motorised valve on the cylinder otherwise it obviously wont work correctly.

So, the bypass would go across the inlet and outlet for the coil in the cylinder?
I can provide more details and photos if they'll help.

Outkast_IRE wrote: »

With newer gas boilers the pump is often built into the unit.

Just an ad lib , i hope you know what your doing if its as simple as it sounds there would only be a few hours work on the plumbing side for a good plumber plus time to drain down and refill . If your not sure what your doing reconsider doing it yourself, i have seen some nasty work over the years from DIYers.

Understood, I'm a sparks and used to work as a pipe fitter, so the electrics and fitting the plumbing parts is no problem. I'm not a heating engineer, that's why I'm asking if there is something I'm over looking on the design side.

I realise a good plumber could do it handy enough, but running the cabling neatly is going to be tricky and will take time to do it properly, I'd like to choose the components myself and would be concerned about getting stung by a cowboy. I also have the time, tools and ability, if I can get a little advise I'm happy to do it myself.

Thanks for your help so far.

HappyHarry

spireland32 wrote: »

Get a plumber or rgi recommend to you by someone else. It's not guess work or a diy job

Thanks for your reply. I agree it's not guess work, and that's why I didn't just plough into it. I don't see why it couldn't be a DIY job for someone with the relevant skills.

I'm just requesting some advise before deciding if it's something I'm happy to do. Is there something fundamentally wrong with what I'm proposing? How would a professional do it differently?

If I get someone in to do it, I still want to know what needs to be done and how it should be done so I know if it's being done right or not.

I've just been to a fiends house that had their boiler replaced and had controls installed and it was a real cowboy job...

Outkast_IRE

Heres a thourough explanation of why you need the bypass valve.
http://www.rwc.co.uk/public/training/qasept02.pdf

As for location of the bypass , it must be location where the closed motorised valves wont stop it from functioning here is some literature and diagrams

http://www.myson.co.uk/static_files/my/media/downloads/ABV_Technical_instruction.pdf

shane0007

I don't see it being a problem for an experienced electrician with experience as a pipe fitter. The automatic bypass valve is exactly as you say, motorised valve failure calling in the pump with the circuit closed, frost protection and pump over-run. Just make sure there is a long enough circuit before the valve. Too many are installed just outside the boiler.

Secondly, the position of the hw water motorised valve. Is your system sealed or vented? Can you achieve the 3 T's rule?

Finally, ensure that you achieve full boiler interlock. Many electricians misunderstand this concept and wire it incorrectly.

Oh and use decent components!

HappyHarry

shane0007 wrote: »

Just make sure there is a long enough circuit before the valve. Too many are installed just outside the boiler.

Thanks for the reply, I'm planning on putting it in the HotPress upstairs, so be about 20' of 3/4" pipe from the boiler.

shane0007 wrote: »

Secondly, the position of the hw water motorised valve. Is your system sealed or vented? Can you achieve the 3 T's rule?

The system is sealed, pressure vessel in the HP. I was thinking of putting the valve very close to the cylinder inlet in the HP.
What is the 3T's rule?

shane0007 wrote: »

Finally, ensure that you achieve full boiler interlock. Many electricians misunderstand this concept and wire it incorrectly.

Thanks for the tip.
I'm planning to connect the room stat and CH output of the controller in series to switch the CH valve, cylinder stat & HW output to switch the HW valve. And use the valve outputs in parallel to switch the boiler. Is there a better way to do it? How do electricians usually get this wrong? (I know not to interfere with the permanent live)

shane0007

HappyHarry wrote: »

Thanks for the reply, I'm planning on putting it in the HotPress upstairs, so be about 20' of 3/4" pipe from the boiler.

That's fine. The ABV are self explanatory. Just follow the direction of the flow to the direction of the arrow to the return on the ABV.

HappyHarry wrote: »

The system is sealed, pressure vessel in the HP. I was thinking of putting the valve very close to the cylinder inlet in the HP.

Just ensure that all circuits have access to the expansion vessel individually. Usually best to have the vessel on the return.

HappyHarry wrote: »

What is the 3T's rule?

A bit harder to explain but basically you will have more T's with an open vented system but rather than confusing you, the first T on the flow pipe from the boiler should be to the flow to the cylinder and the 2nd T is the rads. Likewise FROM the boiler return, the first T is the T to the return from the cylinder and the 2nd is the rads return. Mix these up and you will get what is called reverse circulation which is basically the rads will heat up when the hot water only is on, even with the motorised valve in the closed position.

HappyHarry wrote: »

I'm planning to connect the room stat and CH output of the controller in series to switch the CH valve, cylinder stat & HW output to switch the HW valve. And use the valve outputs in parallel to switch the boiler. Is there a better way to do it? How do electricians usually get this wrong? (I know not to interfere with the permanent live)

They do all sorts, removing SWL from motorised valve, bypassing SWL, wiring stat to PL of motorized valve, etc. etc.
PL from spur to boiler. PL from spur to motorized valves. PL from spur to timeclock. Timeclock SWL to stat. Stat to SWL of motorized valve. Aux of motorized valve to SWL of boiler and circulating pump. Also make sure the room stat has a neutral for the anticipator for accuracy. If not it will have a reaction time of 6C making the stat very inaccurate and unable to react fast enough to varying temps.