Questions, combi-boiler and electric cover door..

Sirbendy

For once, I'm not about to ask about my Promax boiler..heh...

We're moving, to a 2 bed flat about 10 minutes down the road. Where we are now (3 bed semi), we have an A rated Potterton Promax Condenser boiler, with (somewhat aged and mostly duff) TRVs and a room thermostat.

Where we're going to is an upper floor flat, should be warmer anyway. However, it has a Potterton Performa 28i D rated non-condensing combi boiler that seems to be rated "for a large property", circa 2006ish. It has recent looking radiators with TRVs that look like they may work quite well..BUT..it does NOT appear to have anywhere (and we looked 3 times) a thermostat?

So...first question: Which *in theory* is cheaper to run? An A rated system boiler or a D rated combi? I'd think it's be the system boiler, but I can't see the combi working as hard given it's rating, so it may even out.

Question 2: How precisely does one control a combi that has no room thermostat? I see the twiddly knobs for hot water and radiator temp, and I'm guessing the TRVs come into the equation somewhere..but can anyone explain how it works and what I could do to keep it economical?

Unrelated to that, we have a "shared" meter box on the side of the house..slimline thing, housing a prepay meter for downstairs, and a "normal" meter for us. When I tried it to see if it was open..the door fell off! I'm guessing some numpty forgot the key at one point and forced it, and snapped the hinges off...given that rain and electric=no go, what's the best course of action to try and get this fixed up? I taped it shut for now, but I'd feel a lot happier if it was done "properly"..

I also have a gas meter that measures in cubic feet and looks like it belonged in the titanics engine room, in a brick-built enclosure with a wooden door that's rotted away..heh..I can make that a new one though.

Many Thanks!

Cardew

An A rated 'anything' will be more efficient than a D rated anything. You can look up the efficiencies in the SEDBUK tables.

Lots of older CH systems have no room(wall) thermostats, although they are now mandatory on newly installed CH systems.

All you do is set the TRVs on each radiator to achieve the required temperature in each room.

Given that is very difficult to achieve the required temperatures using a wall thermostat*, many people(including me) simply turn the wall stat right up to maximum so it is always demanding heat and rely on the TRVs.

* a wall thermostat in a cold hall makes it difficult to set correct temperatures for a living room, and a wall stat in a warm living room ----

It is not a huge job to fit a more sophisticated control unit with remote sensors in each room if you want.

Sirbendy

Not an option really, unless I can ask my new landlord/lady nicely..heh. I'm guessing the boiler monitors the water temperature of water coming back from the radiators and says "you're not much cooler than when you left, so the rooms are warm enough for the TRVs to be doing their job, so I can turn off now"..is this (broadly) accurate?

I do see where you're coming from though..our room stat is in the kitchen, by the radiator..the ground floor can be icy, but the 'stat will turn off regardless..I think it's very badly sited.

One of the reasons we thought of going back to a flat was that we've abandoned the ground floor this last month apart from cooking and are living upstairs where it's a nice temperature.

Hopefully, since the flat under us will be to an extent warming the floor, the new place won't get quite as cold..