Central Heating in a 3 storey town house

[DoItProud]

I live in a three storey town house on the side of a hill. The ground floor contains the main entrance a garage, utility room and bathroom. The rear wall is backed by earth and there is a stairwell at the back here. on the first and second floor, the stairwell is in the centre of the house (the stairs turn 180 degrees for each ascent). The kitchen is over solid ground to the rear and the lounge is at the front over the garage. The boiler is in a cupboard in the kitchen and the cylinder is in the airing cupboard opposite the stairs.

We moved in in March and the central heating has been off for most of the year so far.

There is only one simple room thermostat at the bottom of the stairwell on the ground floor. Because it gets quite cold down there (and there is only one double radiator) the thermostat is usually set to about 15 degrees for the rest of the house to be at a comfortable temperature.

I have bought a 7 day progammable thermostat that I would like to install in the lounge. The existing controller in the kitchen would then be set to "const" and the temperature/times controlled from this unit.

I have considered that removing the thermostat on the ground floor may result in the temperatures down there dropping below freezing and freezing the pipes. So first question:

Can I leave the ground floor thermostat connected and set to it's lowest temperature in addition to the 7 day controller that would be connected in parallel? - Essentially the ground floor thermostat becomes a frost override for the central heating.

or

Would it be better to eliminate that thermostat and install a secondary heating system for frost protection on the ground floor - perhaps an electric oil radiator or electric underfloor heating - in addition to the existing double radiator.


I have also been fiddling with the controls on the boiler and cylinder The boiler was set to 1.5 and the cylinder temperature sensor set to 65. The water coming out of the boiler only seemed to be coming out at 50 degrees (I have a PIR thermometer that I point at the pipes and boiler). This meant the hot water circuit never switched off and the pump/boiler were constantly running. I turned the boiler up to 4 and the water seems to come out at about 58 degrees now so I turned the temperature sensor down to 55. This has fixed the constant running problem but caused the cylinder to vent into the cold water tank and off out of the overflow.

There is an electric immersion element in the cylinder but it is always off.

Lots of questions:

Should the boiler heat the water hotter than 58 degrees? I think it's less than 10 years old, but I don't believe it is a condenser.

Should I turn the thermostat and boiler up hotter to get the water to 60 degrees? I read that water at 55 degrees can cause legionnaires - is this BS?

Do I need to adjust the float and valve in the cold water tank to lower the normal water level thus reducing the pressure head to the cylinder and preventing the cylinder vent overflowing?

There's also a bit of air being pumped around the boiler circuit - shouldn't this come out of the boiler vent into the small hot water header tank, will it end up in the radiators or do I need to force it out from the drain cock (connecting via a hose to the mains)?

Sorry for asking so many questions, this is the first house I've owned with gas central heating so it's all a bit new to me. I tried to get answers by research but these are quite specific questions I have

I insist on things being done to high standards and some of the electrics in this house are fearsomely bad (socket boxes nailed to the walls, wires with split insulation etc - the potterton junction box was full of overpopulated chocka blocks, bare wires and straggly multi-core, not to mention the fact it was on the wall upside-down. Poor shame!) Luckily I have the time and inclination to rewire it all neatly and safely, unlike the punk/s that installed it.

Your professional advice will be greatly appreciated.

 

[EliteHeat]

the potterton junction box was full of overpopulated chocka blocks, bare wires and straggly multi-core, not to mention the fact it was on the wall upside-down. Poor shame!) Luckily I have the time and inclination to rewire it all neatly and safely, unlike the punk/s that installed it.

So you replaced a plastic strip connector then?

 

[DoItProud]

No I didn't replace anything. It's a potterton PWB1 junction box - it has 11 separate terminals on an integrated strip connector marked A,B,C,D,N,L,1,2,3,4,5 and two 5 terminal blocks at either end. The left hand block is marked N and the right hand one E. Apart from being mounted on the wall upside down, this junction box also contained three separate bits of chocka block - one with all the earth wires stuffed in it, the other with all the neutral wires stuffed in one end. Most of the multicore wires were unsoldered and fraying and the live (ring) wire was connected to strip connector terminal marked N. one of the neutral wires had a slice out of it's insulation with about 5mm of core exposed and one of the live wires had a 20mm spilt with the core exposed along this length.

After isolating the power and making a note of the connections before I started: I mounted the unit the correct way up, moved all the blue neutral wires in the first chocka block to the 5 terminal connector on the left, all the earth wires to the 5 terminal connector on the right, moved the live ring wire to the terminal marked L and the other three wires that were sharing a Chocka Block to one of the spare terminals in the strip of 11.

I only moved one set of wires at a time - I didn't disconnect them all, then reconnect them. As I worked my way through I re-stripped and soldered all the multi-core wires.

I only put one bit of Chocka block back in, in place of the 20mm exposed core I discovered on the live wire.

I have a diagram of the junction box before and after I rewired it.

The heating and hot water systems are still operating correctly, the boiler, valve, pump and thermostats all function as before.

The only thing I have really changed is the setting on the boiler, which I have increased and the setting of the cylinder thermostat, which I have reduced.

 

[DoItProud]

Quick update: There's been no more overflows and the new thermostat is mounted up on the wall ready to be wired in to the junction box.

 

[DoItProud]

In conclusion:

I've wired the new thermostat in between the live and the com terminals that the old thermostat was switching this makes it completely independent from the original potterton controller and thermostat so now both thermostats operate as a logical "or" arrangement. There is no need for the potterton controller to be on for the lounge thermostat to activate the CH. I have set the thermostat on the ground floor down to its lowest setting as planned and I've tested the system still works in all states. I might still add a small electric oil radiator to the ground floor to improve frost protection, but we'll see how we go over the winter.