new condenser boiler tips

[Babz]

We've just had a new condenser boiler installed, our previous boiler was ancient and had a tank in the attic but, although the poor old thing many a time broke down, when it was working we always had lashings of lovely hot water. This new boiler seems to begrudge us every drop of hot water, we can now run a bath without having to add any cold water and it isn't really as hot as we like it (and it takes ages to run, the pressure is so low, though the shower from the bath mixer tap has far more pressure now than it used to) we have the water temperature set at the highest. By contrast the central heating part of it seems determined to roast us alive, we have it on less than half of the maximum temperature on the boiler and even though we use the room thermostat we're either red hot or if it clicks off the radiators cool down and it never seems to drop far enough to come back on, I suppose the air around the stat must be warm but it's sometimes chilly sitting on an evening.

The plumber who installed it was a man of few words and didn't really give us any practical tips, just the instruction book, but what we could do with is someone who has one of these things (Baxi) giving us some tips on the best settings and how to get water as hot as possible from it.....can anyone give us any advice, hints or tips please, at present I'd really like the old boiler back, it was a case of better the devil you know.

Thanks.

[buildersmate]

What else was changed OTHER than the boiler? Was a straight swap?
Your explanation of the changes experienced in the way the thermostat seems to perform is not compatible with merely the boiler being swapped - its just another heat source.
Regarding the HW issue, did you have a combi before, and have you now got a combi?

[Babz]

No it wasn't a straight swap, I don't know much about heating systems or types of boilers but previously we had a small unit in the bathroom and a huge tank in the attic, which I suppose heated up and stored the hot water until we needed it, as opposed to this new condenser one which if I understand correctly heats water on demand.

All I really was asking for were a few practical tips e.g when we want bath water is there a chance of it being hotter if the central heating is on or off at the time. Sorry to be so vague.

[buildersmate]

Ah, it sounds like you had a HW storage tank before and now you have a Condensing Combi boiler.
Combi do work on demand, and there is a maximum rate at which a specific Unit can provide heat. So when the CH is off, more available capacity is available to supply the HW. Try turning the CH off and see what happens to the HW.
One suspects the boiler may be underspec'd. Then again, its been pretty darn cold in much of February so the CH is working to its maximum demand.

[Babz]

Thank you, we'll try that. I thought I read somewhere that due to EEC regulations boilers now have a maximum heat of 60, don't know if that's right but I wouldn't be a bit surprised. I just like a very hot bath. Thanks again

[buildersmate]

You could right about that - needs a fully-fledged plumber like Gucciman to answer that.
You are talking about the maximum temperature (60) that the boiler will heat water to before turning off. That is one factor - the second is the rate at which the boiler is capable of heating water - which drives the maximum flowrate.

[Babz]

Aha now you've blinded me with science. I think we're just going to have to fumble on and learn as we go, after all it's in to stay and the old one has gone to the great scrapyard in the sky so there's no going back!

[gucciman]

what is the power output of your new boiler?

most people who swop from a traditional system to a combi boiler are very dissapointed with the hot water which is why it is so important you buy the most powerful boiler you can afford.

you also need to check that the installer used the correct size gas supply pipe for the boiler has typically a non combi boiler can operate ok on a 15mm gas supply pipe but a combi usually needs a minimum of 22mm gas supply pipe and for really powerful boilers possibly up to 35mm.

so i need to know what the power of the boiler is and what the size of the gas supply pipe is.

the central heating has no bearing on the hot water supply as when you open a hot tap the heating automatically switches off as hot water always takes priority. the exception to this is if the diverter valve is faulty but this is unlikely with a brand new boiler.

the room stat problem could be down to the positioning of it, it should never be near a radiator, in the same room as a thermostatic radiator valve or near to any other heat source such as a fire or a cooker. you may also consider an upgrade to a better quality room stat such as a honeywell one with a heat anticipator which allows more accurate temperature control.

[Babz]

Thank you gucciman, I think your comment that most people who switch from a traditional boiler to a combi are disappointed has probably summed it up.

As to all the other points, well the truth is it isn't my house and it wasn't my choice of boiler, my landlady pretty much left it to the plumber (who she knows and trusts) to order and install the boiler and I would imagine they agreed a price between them that she could afford.

I suppose the old boiler came into the category of good old British workmanship, it lasted a long time. I've been here ten years and it was here long before me, and despite it's off days it was a good one and gave us endless scalding hot water. I bet this new one doesn't last as long.

Looks like it's going to be a case of get on with it and get used to it.

Thanks very much gucciman and buildersmate for all advice.