Coverting Y-plan to S-plan ???

[lchris21]

Meanwhile back at the Y to S-plan dimema

on to the controls

I'm thinking Honywell S-plan pack for ease of use, compatibility and good reputation. Not the smartfit which seems easy plug and play stuff, as they only seem to have two outputs for CH & HW valves? I need three!!

So, I need to get an extra 2 port valve for the UFH loop, plus a programmable room stat to control this?

Will I be able to integrate the extra prog room stat into the wiring center without too much

Cheers

 

[rayburner]

When I looked into running the underfloor circuits separately I was told to
fit a blending valve from the existing boiler flow/return then another pump and a motorised valve. The room stat sends a signal to the valve to open then the switch in the valve turns on the pump. Not sure you'd need the valve if you only have one ufh circuit and the boiler is running-just use the stat to turn on the pump.

Regarding comments on running ufh of the rad system-did any of you try it ?
Running the ufh circuits from the radiator returns and using trvs keeps floor temps well within acceptable. The only problem is it takes longer for the slab to heat up due to lower flow rate and rads shutting down. The bare foot test tells the story

 

[mysteryman]

This can be done with a second Y Plan valve, which will give you all the control flexibility you require. But, it will need careful wiring, and there is more flow resistance to the heating circuits, as they are both going through two valves.

A three 2 port valve layout may be better, but you would need a permanently open small rad or towel rail as a bypass.

 

[Agile]

Ray, whilst I am sure that you mean to be helpful but you are giving suggestions which are not what a professional installation would comprise.

If you dont have a motor valve then the system pump, when on for rads, will push hot water into the UFH when its not required.

Similarly putting UFH in series with a rad returns will only enable it to be heated when the rads are on.

The whole ethos of UFH is to time it to start heating the two hors before the heat is needed in the rooms AND to stop it an hour before the heat period ends.

Tony

 

[rayburner]

Agile
I appreciate your comments and as I stated it's not ideal to run a UFH system from the rads but in my particular situation it was the most practical way of adding 2 small ufh zones to predominately rad heated areas and it does work OK. I do have another larger ufh zone 12ft x 12ft with 100mm screed and this just doesn't heat up hardly at all unless the heating is on for a long long time the original old 8mm microbore feed to the rad just can't flow enough so I have to re think this area.
I was told by a heating engineer that water cannot flow through a pump when it is off so in effect the pump acts as a shut off valve but I don't know whether he is accurate with this info and I don't know whether a room stat has the capability to switch the supply current for a CH pump on it's own without the motorised valve. I'd like to learn from experts on here about stats,pumps and valves.
My whole heating system is unconventional

 

[Agile]

Agile

I was told by a heating engineer that water cannot flow through a pump when it is off so in effect the pump acts as a shut off valve but I don't know whether he is accurate with this info

I don't know whether a room stat has the capability to switch the supply current for a CH pump on it's own without the motorised valve. I'd like to learn from experts on here about stats,pumps and valves.
My whole heating system is unconventional

That was not much of a heating engineer if he was not aware of how CH pumps are constructed! Water will flow through them if there is a head available such as from another pump.

At first sight a room stat might seem able to switch a pump. However, a pump is a very inductive load and a relay is needed, ideally with a snubber circuit otherwise the contacts on the stat would quickly become burnt.

Tony

 

[rayburner]

So I guess use a stat to power the motorised valve and use the mechanical switch inside the valve to turn on the pump is the way to do things ?

 

[kevplumb]

If you are contemplating a new boiler as well, you could try a Viessmann Vitodens 200-W System boiler with weather compensation and 'Sub mounting kit with mixer'. This has three pairs of pipes: one each for the cylinder, radiators and underfloor. The boiler will control all three zones on 7 day electronic timing, everything is plug-and-play, and the only mains wiring is the power supply from the fused spur to the boiler.

why dont you use the free advert as a sig

christ you post it often enough

 

[Agile]

The old simple thermostats had big contacts and were no problem controlling a pump.

However, anyone who repairs boilers knows that the pump relay is often a common failure point even though they are often 8A relays.

Most of the current electronic stats and programmers are expected to be used to control a boiler call for heat which takes hardly any current.

Whilst the manufacturers like to say their products are still suitable for controlling pumps, they use very tiny relays and I would not risk the early failure of an expensive component by using it to control a pump which was not fitted with a snubber circuit.

Tony

 

[kevplumb]

slightly off topic but

whats a snubber circuit. tony

as opposed to using a cap ???

 

[Agile]

Its a resistor ( about 100 ohms ) and a capacitor ( about 0.1 uF ) in series often in a single package.

They were used on the gas valve connections of many of the old BBUs and one was added as a mod when a Solo (?) or similar boiler PCB was replaced.

They absorb the inductive spike when the supply to the pump is switched off and prevent burning of the contacts. They should be included in boiler PCBs but by saving two components the relays will hopefully fail after a few years after the warrantee has ended so they can sell a new PCB.

Tony

 

[kevplumb]

They were used on the gas valve connections of many of the old BBUs

ahh a suppressor stops the tv interference as well when the gas valve operates

with you now

 

[rayburner]

If you are contemplating a new boiler as well, you could try a Viessmann Vitodens 200-W System boiler with weather compensation and 'Sub mounting kit with mixer'. This has three pairs of pipes: one each for the cylinder, radiators and underfloor. The boiler will control all three zones on 7 day electronic timing, everything is plug-and-play, and the only mains wiring is the power supply from the fused spur to the boiler.

why dont you use the free advert as a sig

christ you post it often enough

I'd love a new boiler and I even put a pair of 28mm pipes for as and when the need arises but I'm on oil and have poor mains water pressure which means a gas combi is not an option