Boilers, again. Talk to me about combi boilers with storage tanks!

[wendybird77]

I know it is thrilling, but I have to make a decision about what CH system to put in. I've had 3 plumbers tell me 3 different things and give me very different costs. The house is large end terrace, 3 beds, will have 1 bathroom (shower and bath). Eventually will likely have another shower room and would like to future proof for this. I want lots of hot water. DH and I take long showers to get away from our small children. Eventually we will have teenagers who take long showers. Whilst taking these long showers I don't want the water pressure and temperature to go all funny because someone flushes a toilet or turns on the washing machine or dishwasher. I don't want to run out of hot water because DH nipped into the shower before me.

I don't want an electric shower. We have one in the annex for emergencies when boiler breaks down.

Currently we have an old, closed system with conventional boiler with HW tank in our bedroom and cold storage in the loft. The boiler and the HW tank have to be moved no matter what system we choose. I am creating a cupboard for the boiler / tank / water softener - so space / size isn't too much of an issue.

Water flow is good from both hot and cold bath taps (28 L / min). Pressure is good.

Is a storage combi boiler the answer? Anyone have one and can report? Is a conventional boiler with a megaflo system what I want? I am so overwhelmed with expensive choices I can't get my head around it all!

Any help, experiences, other options are gratefully received.

We have a mains pressure system (no roof tank and mixers work smoothly) and a 240 litre hot water tank in the airing cupboard.
Boiler is gas but hot water is heated by solar thermal (NOT PV) panel on the roof and a backup immersion if needs be.
The panel does all hot water (3 showers one bath back to back) from April to October and does about 1/3 of the hot water in the winter.

When we did the new boiler (Vaillant - worth the extra) and tank and panel, the panel and specialist tank added around £2000 to the bill but our gas bill in the summer is nil. For ever.

Ah. That is interesting. I hadn't considered solar as figured it would cost too much, but we do have a south facing roof. Would you mind giving me more specifics of cost??

Ours was done four years ago and due to a cockup we only have one panel on the roof not two. But
The panel itself cost around £800, Fitting cost around £500, The tank cost around £700. Everything else was standard
www.energysavingtrust.org.uk/Generating-energy/Choosing-a-renewable-technology/Solar-water-heating

I've just had a boiler replacement and personally wouldn't go anywhere near a combi if you have a family sized house, besides which no way would I want to lose my tank & airing cupboard & immersion as a backup.

We replaced regular boiler with a new regular boiler - also replaced pump, tank at same time as they were pretty ancient & cheaper to do in one go. The plumbers quotes did vary widely though in terms of boiler size and I did a lot of online research and checking. The guy I went with in the end was actually one of the higher quotes but felt he was the one who knew what he was doing.

May be worth getting a brit gas quote as comparitor

I am desperate to lose the airing cupboard - I need the space for a wardrobe for DH! The storage combi is appealing as it has an integrated HW tank to compensate when two taps run at the same time - which seems to be the main drawback of the combis. Having said that I've never actually had a combi. Maybe I should stick with regular boiler! Though a large HW tank may be required as the current one only does a shower and a half, which is a pretty big drawback for us. A large tank means I will lose the flexibility to put a shower back in the downstairs loo as well.

Talkin what panels did you use? Are you happy with them? I hadn't been thinking solar now, but this may be the time to do it since we are already tearing the house to pieces and spending our life savings . Did you need someone special to do the installation or was it all done by the same people? Very wary of solar panel installers - the whole industry strikes me as a bit 'double glazing'.

Wendy
This is who now sells what we bought.
REmember these are thermal panels, not PV. WE bought Vaillant accredited.

www.1worldsolar.co.uk/solar-thermal.html

forgot link!

Actually, I have just read that link Talkin. The average installation cost is £4800, but the annual savings is just £55? Really? Not sure that makes financial sense for us, though it seems you got it set up for far less than that. Hmm.

We had a loft conversion done 2 years ago, we replaced the boiler at the same time. We went for a combi Vaillant ecotec. It works fine for us, and we're a four bedroom, 2 bathroom, 4 person family.

I find the saving figures odd on ALL of those sites - we are getting nearer £200 a year and the incremental cost was around £2000 .....

I had a combi installed almost 5 years ago. When I use 2 taps at the same time the pressure on both reduces.
Also boiler pressure needs checking and increasing if necessary.
This morning, there was no heating on, so went to boiler and 2 lights were flashing, the blue one which shows it is on and a red Alert Button flashing madly, which I pressed but nothing happened. Increased the pressure as a bit low, then pressed the red Alert buttton again but held it pressed, and then lots of struggling noises and came on.

What a carry on at 7am. Not good in the cold and in panic. Worried it will happen again as no idea what caused it.

Well I've a gentleman coming from BG next week to do an assessment about energy saving measures for the house, I'll ask him about solar water heating. We plan to be here longer term, so a 10 year investment would be ok for us, particularly as it seems the right thing to do environmentally. Good to know you save closer to £200 - that is a bit more encouraging!

Ihatemytoes I was looking at the ecotec ones - they do a storage combi as well. No pressure drop then?

Digerd It is an awful time for a boiler breakdown! Our current boiler I have to increase the pressure on too. I hope it lasts us another month until I get a new one sorted out.

I hate the pressure on this decision, so much money and faff if I make the wrong choice!

I don't understand storage combi. Mine can be set to have instant hot water having a small storage, but I have it on eco as my boiler is in the cold garage, which has never gone below +5c even when -10 outside, as I checked with a min/max thermometer.

I have 3 sets of solar tubes which heat the water all year round and can be used as background heaters for the rads in summer if needed, best thing I ever bought next to the woodburner resulting in practically zero heating and warm water costs.

Bureni - can I ask what solar tubes you have and who installed them? I'm very interested in solar if I can justify it.

We have good mains pressure so opted for a megaflop system with a powerful 'normal' boiler. We have two bathrooms and three teens. The megaflow hot water cylinder along with our Glowworm 30 cxi (I think) means we have loads of hot water with great pressure. We upgraded all our pipework to 28 mm which is the same as the water supply pipe. Our megaflow cylinder takes up quite a lot of space.

The hot water and heating warms up very quickly. We never run out of hot water.

good explanations here

Hopefully pigletjohn will post some advice, he/she knows what he/she is talking about. unlike me and is Mumsnets resident expert

I have been very impressed with megaflo type systems. You have unusually good flow which is ideal.

You should be able to have an immersion heater fitted to it so you will have a backup hot water supply when the boiler goes wrong.

IME combi boilers go wrong more often than conventional boilers. This might be because they are more complicated and have more in them to go wrong.

I am not convinced of the cost:payback of solar, sorry.

As for people who think that removing a cylinder will solve their domestic storage problems, I am of the school of thought that if you give people more cupboards, all they do is put things in them. This may be unsympathetic, but I certainly have no difficulty in filling cupboards.

Digerd

If your system keeps losing pressure, then it has a leak. Look at the outside wall where the pressure relief valve exits behind the boiler, see if there are marks of water.

If you can't find the leak it might be from a radiator pipe under the floor.

Wendy

Your 28lpm

Is that from the tank or the main?

Loft tanks can give very good flow at the bath taps, but if you intend to do away with the tank, you need to measure the incoming flow from the main at the kitchen sink cold tap.

Had the British gas < gorgeous young man> engineer, round as it did it again this morning, despite 5 times pushing the reset button, the noises it was making were struggling ones and there was water dripping at the bottom side
But after an hour it suddenly got going again and the pressure went up to 2.5.
Engineer arrived very quickly, and checked boiler, and found the condensing container in the boiler and the thin pipe connected contained lots of dirt and cleaned it out.
Just hope it's OK tomorrow morning. As this is the 2nd time it happened.

The pressure was fine @ 1.5 this morning when it wouldn't get going properly.

"the pressure went up to 2.5"

does the pressure vary a lot between hot and cold? that can happen if the expansion vessel needs pumping up (it is supposed to absorb the expansion of hot water and prevent the pressure rising too much).

excess pressure would make your pressure release valve drip and lose water. Once a PRV has started to drip it will often not seal tight again and will continue to drip until cleaned or replaced. Are there marks of water outside the house on the wall behind the boiler?

If you are on a BG contract they will probably reinflate the pressure vessell or change it. Same with the PRV if it continues to drip.

Try to keep your hands off the engineer or they will make a note and send you ugly old ones in future.

Piglet
I'm too old to be groping - it was a purely aesthetic appreciation and he had a lovely polite manner, which I appreciate too .
I don't look at the pressure much as boiler in attached garage to kitchen and is cold in there. But last time it was 1.5 when I looked.
He wrote down that he "unblocked condenser trap".
Asked him if the diverter valve was OK and he said "Yes"
"Flue fine, Emission/combustion test fine, Burner settings correct"
He was there a long time testing everything.
Once the heating had got going the dripping stopped, before he came.

Piglet the 28 L / min is from both the hot and cold. The hot is from the HW tank (obv) and the cold is mains pressured (sprays everywhere when you try to stop it at the basin). The flow from the kitchen tap is about 14 L / min, but that is not where our stopcock is located and has a very cheap tap on it (which we are replacing shortly).

I agree with your assessment of cupboards, we are removing the airing cupboard from my bedroom which will leave room for 2 wardrobes for 2 people and all the linens are going into the purpose built cupboard in the new bathroom! One of the plumbers has suggested a floorstanding conventional boiler with a large tank as well, which will mean I cannot ever put a shower back into the downstairs loo. Not the end of the world, but I would prefer a more compact system that leaves me more flexibility - such as a wall mounted boiler and tank on the floor under? Or the vitodens 222-f which I've also had a quote for. I'm also having a water softener put in at the same time, so maybe that will have an impact too?

I am very pleased with the quality of my Viessmann Vitodens (different model). Make sure it is one of the Approved Installers (see their website) and you get their extended warranty. Parts are expensive.

the 222 stores some hot water, and heats more while you run your bath, you are combining the newly-heated with the stored, so is said to be able to fill a hot bath quickly, which combis generally can't do. It is quite big and heavy.

Possibly you have a 25mm plastic incoming water main, upgrade the internal stopcock if it is smaller, and you may need to run 22mm pipes all the way to the bath taps, any length of 15mm pipe, and especially service valves, will restrict the flow.

The water softener will restrict the flow somewhat, ask for large-bore hoses and valves (they will cost extra) and specify to the installer that you don't want any 15mm pipework or valves round it (they are the usual ones).