Help please with spec for central heating for 1 bed flat

berg222 · 9 Sep 2014

I am specifying a wet central heating for a rented out 1 bed flat.
W-Bosch Combi boiler + 5 radiators + portable wireless thermostat.
I would like all radiators to have TRVs so tenants are able to turn off all radiators apart from in the room that they want to heat.

I have had 2 quotes & been advised that the installation needs to ensure water continues to circulate for as long as boiler is above its safe internal temperature. This to be achieved by having 1 radiator (hall usually chosen) not having a TRV but to be always open & on.

But this means tenants always having to heat the hall when have heating on. But no one wanting to heat their hall. This is waste of energy & money. Are there any alternatives to having 1 of radiators without a TRV. Such as a correctly positioned automatic bypass valve providing the required circulation & heat dumping capability.

Looks good in theory. Hall radiator is only used for heating the hall. Only turned on when required which is rarely. ABV opens when radiators unavailable but otherwise closed. More energy efficient.

Would this work. Thanks for any comments.

Dean744PiN5 · 9 Sep 2014

what your proposing will actually use more gas than is necessary and most likely will cause unnecessary and wasteful short cycling.

If you want to keep gas bills to a minimum have a boiler with a wide turn down ratio fitted such as the vokera linea one which can modulate down to 4kw heating output, whereas the worcester is around 7kw meaning at time of the year where only 4-5kw's of heating is needed the worcester will use up more energy via short cycling (turning itself on and off).

Also look at having weather compensation fitted which again will help to improve efficiency, reduce bills and increase comfort by automatically adjusting the temperature of the radiators to suit the outside temp (hotter rads when cold and cooler rads when milder) .

Of course all this whilst inexpensive requires the user to educate themselves to get the best of the system and out of the mind set "yeah i'm not cold but the rads aren't baking hot"

blimey alec's teachings have really rubbed of on me

D_Hailsham · 9 Sep 2014

berg222 said:
W-Bosch Combi boiler + 5 radiators + portable wireless thermostat.

Wireless stats are not installed because they are portable, but because they are easier to install. The "portable" part should still be installed in a fixed location.

I have had 2 quotes & been advised that the installation needs to ensure water continues to circulate for as long as boiler is above its safe internal temperature. This to be achieved by having 1 radiator (hall usually chosen) not having a TRV but to be always open & on.

Put a TRV, set low, on the hall rad, but not on the one in the living room; and install the thermostat in the living room.

If there is a TRV in the same room as the thermostat, the TRV must be set to max.

flameport · 9 Sep 2014

berg222 said:
I would like all radiators to have TRVs so tenants are able to turn off all radiators apart from in the room that they want to heat.

TRVs are not fitted so that the radiators can be turned off. They are there to open/close the valve in response to the air temperature.

Heating a single room in a property is inefficient, unless that room has high levels of insulation between it and the adjoining rooms, and the door is permanently closed.

vulcancontinental · 9 Sep 2014

Thank you for mentioning the Linea One Dean but it's 38KW for DHW and 15.6l/m which is is only useful if the flat has a cold supply that good.

If the flat has a lower supply pressure and flow rate the Unica i also has a 10:1 turn down ration and is 28, 32 or 36 KW so obviously the 28 can give 2.8KW to the heating and 11.8 l/m of DHW.

Easy to put in WC on any of them but sometimes in a flat it's difficult to locate the sensor on a suitable (North or North/West) wall. Maybe the Open Therm modulating thermostat would be a better option but the occupier has to be a bit tech savvy.

TRV's in a house, never mind a one bed flat, are often a waste because of lack of space as furniture, curtains, in fact anything that restrict the air flow across them means the blessed thing has to be left wide open to get the thing to open anyway.

Agile · 9 Sep 2014

D_Hailsham said:
Wireless stats are not installed because they are portable, but because they are easier to install. The "portable" part should still be installed in a fixed location.

I really do disagree with that statement.

Most of those that I install are seen as a very useful energy saving feature whereby the customer takes it to bed and turns off the heating when getting into bed.

In the morning the heating is turned on a few minutes before getting up.

Thus the heating is only on for the minimum time!

Tony

Justin Passing · 10 Sep 2014

Mr Landlord, be careful
If you encourage your tenant to keep rooms cold, you risk condensation in them. The tenant complains, stops paying rent, and YOU have to deal with the problem and the mouldy walls, his mouldy clothes, etc.
Making the system efficient for him is of little direct benefit to you. If you get just one callout because he doesn't understand it, or it isn't working the way he thought it would, or he's forgotten, YOU pay. Weather compensated systems tend to be like that.

Building Regs (I believe, you can check) demand TRVs only in the bedrooms. If you do use them in all rooms (Other than the living room where the thermostat can go) you can set some types with pins inside the head to stop the tenant turning them right off. That stops the rooms getting too cold (condensation) relative to the others.

Don't overestimate the sophistication of your tenant. Digital 7-day timers are beyond the "can't be ar*ed" limit for many of them. A typical Australian (or warmer country) tenant will ask "What's a thermostat?". They may have never seen one before.

Wireless thermostats have batteries in the sensing end. Tenants are likely to see them as something you should change, and you get a callout because it's "not working".

Portable thermostats are carried about, dropped and then also "not working". Timers are for turning the heating on before the occupier gets out of bed.

Make sure you explicity forbid them to dry any clothes on the radiators, too

D_Hailsham · 10 Sep 2014

Agile said:
D_Hailsham said:

The "portable" part should still be installed in a fixed location.

Click to expand...

I really do disagree with that statement.

I did say "should", not "must".

Most of those that I install are seen as a very useful energy saving feature whereby the customer takes it to bed and turns off the heating when getting into bed.

In the morning the heating is turned on a few minutes before getting up.

Thus the heating is only on for the minimum time!

But does the house temperature rise to the required level in the few minutes before getting up? Or is it just a case of the rads feel hot enough.

You can spend just as much heating the house for an hour or so in the morning and a few hours in the evening as someone who keeps the heating on at a constant temperature all day.

Agile · 10 Sep 2014

It is a common misconception that its no more expensive keeping heating on all day!

TRVs should be fitted onto ALL rads and the only exception is the room where the stat is fitted.

An auto bypass valve is also needed.

Tony

berg222 · 10 Sep 2014

dean7445 said:
what your proposing will actually use more gas than is necessary and most likely will cause unnecessary and wasteful short cycling.

If you want to keep gas bills to a minimum have a boiler with a wide turn down ratio fitted such as the vokera linea one which can modulate down to 4kw heating output, whereas the worcester is around 7kw meaning at time of the year where only 4-5kw's of heating is needed the worcester will use up more energy via short cycling (turning itself on and off).

Also look at having weather compensation fitted

Good point about having wide ranging boiler that can power all rads but also able to modulate down to 4 KW - would guess that's what needed for background warmth to 1 room. Need to look again at boiler selection. Shortlisted these brands as reliable with good after sales service and guarantees that honoured. Glowworm, vaillant, ideal logic +, W-Bosch - will check specs - look at full range of features including range of heat output. Also read t&cs of the guarantees - would want at least 5 yr parts & labour.

berg222 · 10 Sep 2014

dean7445 said:
what your proposing will actually use more gas than is necessary and most likely will cause unnecessary and wasteful short cycling.

Also look at having weather compensation fitted which again will help to improve efficiency, reduce bills and increase comfort by automatically adjusting the temperature of the radiators to suit the outside temp (hotter rads when cold and cooler rads when milder) .

Never heard of weather compensation - this new to me. Will google.

berg222 · 10 Sep 2014

D_Hailsham said:
I have had 2 quotes & been advised that the installation needs to ensure water continues to circulate for as long as boiler is above its safe internal temperature. This to be achieved by having 1 radiator (hall usually chosen) not having a TRV but to be always open & on.

Click to expand...

Put a TRV, set low, on the hall rad, but not on the one in the living room; and install the thermostat in the living room.

If there is a TRV in the same room as the thermostat, the TRV must be set to max.

If we had non-TRV rad in living room means this room would always be heated when heating is on. Tenant would not have option of turning off the living room heating. But this room often only required to be heated in evenings. In day time it would usually be kitchen that heated. Tenants will not want to heat empty rooms. I am trying to find out if we can have all rads with TRVs with heat dumping provided by ABV and without the fixed thermostat and its associated non-TRV radiator. I would not want a TRV radiator in same room as thermostat as TRV could get turned off with stat calling for heat for hours.

berg222 · 10 Sep 2014

flameport said:
berg222 said:

I would like all radiators to have TRVs so tenants are able to turn off all radiators apart from in the room that they want to heat.

Click to expand...

TRVs are not fitted so that the radiators can be turned off. They are there to open/close the valve in response to the air temperature.

Heating a single room in a property is inefficient, unless that room has high levels of insulation between it and the adjoining rooms, and the door is permanently closed.

I always use TRVs as on/off switches - is there another way for tenants to easily turn rads on/off in rooms you don'nt want to heat.
The tenants always keep doors and windows tightly shut. Advising them that heating entire flat would be more efficient would be hard sell. I would guess more gas would be used even if just to 18 degrees say.

D_Hailsham · 10 Sep 2014

berg222 said:
I always use TRVs as on/off switches - is there another way for tenants to easily turn rads on/off in rooms you don'nt want to heat.

In that case you are wasting money on TRVs; just install standard wheel head valves.

berg222 · 10 Sep 2014

D_Hailsham said:
berg222 said:

I always use TRVs as on/off switches - is there another way for tenants to easily turn rads on/off in rooms you don'nt want to heat.

Click to expand...

In that case you are wasting money on TRVs; just install standard wheel head valves.

Did not realise that was an option. The council housing dept & building control all pushing TRVs. To comply with Part L to make the installation as efficient & controllable as possible. To enable tenants to keep down heating bills. No local RGIs mentioned wheel head valves. But also need capability to adjust each rad individually from v low background warmth to 21 degrees. So need on/off/adjustable rads. Can wheelheads but turned to any position to control heat output ? Benefit of TRVs is they maintain the temperature of a room within a narrow range - assuming they accurately measure and respond to room temperature. But in practice do they do this reliably.

Doubt there would be any cost saving on minor changes to spec. Would expect the same cost whatever arrangement of wheel head valves & TRVs we specify. If we went for a cheaper boiler or fewer rads would expect cost adjustment. Contractors good negotiators – they hold their quotes well – not easy to shift.

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Help please with spec for central heating for 1 bed flat

Dean744PiN5

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