as far as i know it just keeps the primary heat exchanger and boiler circuit warm (about 10 litres?) all the customers that we installed 831/7's have been more than happy with the near instant delivery of hot water. the beauty of warm start when used in conjunction with the 140 timer is that you can set 3 times a day when you want instant water and not use the facility at night or during the day when out at work. you still get normal combi operation in the off periods just take a few seconds longer for the water to get up to temp.
Valiant 937 ecotec Combi boiler
- Thread starter rizsher
- Start date
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Guys,
My woes just went supernova
, see //www.diynot.com/forums/viewtopic.php?p=1457690#1457690
Quick advice, 937 or 837, or do Veissman do a similar combi boiler with warm start that the experts here will agree on?.
Thanks.
Riz
My woes just went supernova
, see //www.diynot.com/forums/viewtopic.php?p=1457690#1457690Quick advice, 937 or 837, or do Veissman do a similar combi boiler with warm start that the experts here will agree on?.
Thanks.
Riz
The OP clearly had an open view about a combi or stored HW system. Nowhere did he say he only wanted just a combi.
I dont see why you think that a storage combi will run two showers all day. I agree two small ones but not a nice one that needs a good flow rate. What do you imagine happens when the store is depleted?
Its surprising that you apparently dont know how the Vaillants operate their preheat. They run the burner until the plate HE is hot and then turn off the burner. It does not specifically keep the main HE hot as the control is from the sensor on the plate HE.
To the OP, take great care with choosing a new system!
Tony
The three plumbers are correct. Your house currently needs a 30kW boiler, assuming a hot water cylinder. However if you install better loft insulation it reduces to 22kW and cavity insulation would reduce it to 16kW. These figures exclude the extension you mentioned earlier.
You have not explained why cavity insulation is not possible.
Boiler specs can be misleading. To say that a boiler can deliver 39kW for HW and 28 for CH does not mean it can deliver both at the same time; it's either one or the other.
Why are you so keen on a combi boiler?
PS Sorry to read about your woes in the other post.
If you want to get the boiler replaced asap, the obvious solution is either a system boiler or a heat only boiler as they will take less time to install and there will not be so much upheaval.
A Remeha Avanta 30S or 30V would fit the bill nicely.
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Oops....
D Hailsham has fallen into his own trap there.
All three plumbers were WRONG to say you needed a 30 kW boiler! But they are only interested in their own pockets and not their customers. Thats why I feel so happy advising customers because I am not thinking about my income.
You need loft insulation and a 24 kW boiler!
I would be surprised if you will really need anything significantly larger than a 24 kW boiler unless the extension will be very large. It will have far better insulation and potentially could even lower the heat input required by improving insulation to the house.
I am also interested to know why you think you cannot have cavity insulation ( if you have a wall cavity ).
There are different systems and will mostly reduce the heat loss by up to about 25%. Thats very significant.
Tony
D Hailsham has fallen into his own trap there.
All three plumbers were WRONG to say you needed a 30 kW boiler! But they are only interested in their own pockets and not their customers. Thats why I feel so happy advising customers because I am not thinking about my income.
You need loft insulation and a 24 kW boiler!
I would be surprised if you will really need anything significantly larger than a 24 kW boiler unless the extension will be very large. It will have far better insulation and potentially could even lower the heat input required by improving insulation to the house.
I am also interested to know why you think you cannot have cavity insulation ( if you have a wall cavity ).
There are different systems and will mostly reduce the heat loss by up to about 25%. Thats very significant.
Tony
D_Hailsham:
The reason I don't think cavity insulation is not possible is mostly anecdotal based on the few plumbers who have come to the house in the last 2-3 weeks to give me a quote for the new boiler. However,the BGheating engineer, who contended I don't need more than 20 kW also stated that my house cannot take cavity wall insulation, reasons, I don't really know. When the B&Q ppl come to install the loft insulation, I'll ask them to check the building out and advise.
I understand a combi can not deliver both heat outputs simultaneously, but generally, hot water demand would be for fairly short bursts, we're not really bath ppl, a nice powerful shower is what we prefer, and given the house has only 1 bath (with a shower cubicle) and 1 shower room, and there are only 3 of us, myself, wife and 2.5 yr old son, I don't envisage simulatenous h/w usage to be a problem.
Thanks for your kind words; my family were supposed to return from the motherland tomorrow after being away for almost 5 weeks, was really looking forward to meeting the little one, however, with the latest heating debacle, I've told them to stay put while I get this sorted, so they're not coming back another 8 days.
SO, getting a new boiler is suddenly mega urgent.
The reason I'm keen on combi's is quitely simply, its seems a much simper system (on a macro level atleast), not h/w cylinder, no tanks in the loft etc etc. I was not too keen on combi's initially... the idea of a h/w cyliner with immersion heater backup was quite appealing, however, since the boiler went down last night, I've realised if the boiler ever goes down again, I'll not be staying in the house. Aberdeen winters are Baltic, and even right now I'm crashing at a friend's place.
The company I've been talking to [have gotten quotes from 3 installer, plus BG (who refused to quote) and HydroElectric (who were REALLY keen to quote and gave me a price almost 75% more than the highest quote I had received), and decided on this one], are authorised installers for Viessmann and Vaillant (and I believe Baxi too), and hence installing through them gets me 5 years warranty, which I'm really keen on, and hence, with the sudden urgency added to this rigmarole, your suggestion of Remeha Avanta would be difficult to pursue as I'll have to get another cmpany to come in, do the survey, then come back with a quote.
I think I have to choose b/w either the Viessman or a Vaillaint... combi system (I'm actually getting ALL the radiators in the house changes out too, the existing ones are about 30 (or maybe more) years old single panel radiators with no TRV (which itself may not be such a big problem), but also have about 15 coats of thick paint on them. So, all in all, I might as well go thru the disturbance all in the one go and get a combi installed.
So, again, millions quid question.... Vaillaint 837.. (with comfort start), or a Viessmann combi boiler... 100 or 200, I'm not sure, as don't really know what the difference b/w the two is!!!.
Thanks for your assistance.
Riz
The reason I don't think cavity insulation is not possible is mostly anecdotal based on the few plumbers who have come to the house in the last 2-3 weeks to give me a quote for the new boiler. However,the BGheating engineer, who contended I don't need more than 20 kW also stated that my house cannot take cavity wall insulation, reasons, I don't really know. When the B&Q ppl come to install the loft insulation, I'll ask them to check the building out and advise.
I understand a combi can not deliver both heat outputs simultaneously, but generally, hot water demand would be for fairly short bursts, we're not really bath ppl, a nice powerful shower is what we prefer, and given the house has only 1 bath (with a shower cubicle) and 1 shower room, and there are only 3 of us, myself, wife and 2.5 yr old son, I don't envisage simulatenous h/w usage to be a problem.
Thanks for your kind words; my family were supposed to return from the motherland tomorrow after being away for almost 5 weeks, was really looking forward to meeting the little one, however, with the latest heating debacle, I've told them to stay put while I get this sorted, so they're not coming back another 8 days.
SO, getting a new boiler is suddenly mega urgent.
The reason I'm keen on combi's is quitely simply, its seems a much simper system (on a macro level atleast), not h/w cylinder, no tanks in the loft etc etc. I was not too keen on combi's initially... the idea of a h/w cyliner with immersion heater backup was quite appealing, however, since the boiler went down last night, I've realised if the boiler ever goes down again, I'll not be staying in the house. Aberdeen winters are Baltic, and even right now I'm crashing at a friend's place.
The company I've been talking to [have gotten quotes from 3 installer, plus BG (who refused to quote) and HydroElectric (who were REALLY keen to quote and gave me a price almost 75% more than the highest quote I had received), and decided on this one], are authorised installers for Viessmann and Vaillant (and I believe Baxi too), and hence installing through them gets me 5 years warranty, which I'm really keen on, and hence, with the sudden urgency added to this rigmarole, your suggestion of Remeha Avanta would be difficult to pursue as I'll have to get another cmpany to come in, do the survey, then come back with a quote.
I think I have to choose b/w either the Viessman or a Vaillaint... combi system (I'm actually getting ALL the radiators in the house changes out too, the existing ones are about 30 (or maybe more) years old single panel radiators with no TRV (which itself may not be such a big problem), but also have about 15 coats of thick paint on them. So, all in all, I might as well go thru the disturbance all in the one go and get a combi installed.
So, again, millions quid question.... Vaillaint 837.. (with comfort start), or a Viessmann combi boiler... 100 or 200, I'm not sure, as don't really know what the difference b/w the two is!!!.
Thanks for your assistance.
Riz
If you have two shower rooms then I would recommend a cylinder system. You probably dont need to change you existing cylinder now or even later. Its looks quite modern!
You will then have plenty of hot water and not be flow limited as no one seems to have even measured your mains flow rate!
You will be able to have immersion heater backup ( which you should have now anyway ).
Another point and my hobby horse perhaps is about the "motherland". Since you are well established in the UK, I dont see why you have to think of any other country as a "motherland" or specifically to spend too much time visiting old relatives there. Probably more convenient and perhaps cheaper to bring them over here so they can help to look after 2.5 y.o. so you and wife can go out a bit.
Having said that my experience in Scotland finding anywhere to give me a good meal has been very poor! I seem to remember an Indian restaurant somewhere on the East Coast with a burly ( white ) Scotsman serving the food in a very unsympathetic way. Another hotel restaurant closed its kitchens at 9 pm in Dundee ( The George! )
I used to travel a lot with my work for the BBC and Scotland, whilst having wonderful countryside and friendly people, was a disaster for food!
Tony
You will then have plenty of hot water and not be flow limited as no one seems to have even measured your mains flow rate!
You will be able to have immersion heater backup ( which you should have now anyway ).
Another point and my hobby horse perhaps is about the "motherland". Since you are well established in the UK, I dont see why you have to think of any other country as a "motherland" or specifically to spend too much time visiting old relatives there. Probably more convenient and perhaps cheaper to bring them over here so they can help to look after 2.5 y.o. so you and wife can go out a bit.
Having said that my experience in Scotland finding anywhere to give me a good meal has been very poor! I seem to remember an Indian restaurant somewhere on the East Coast with a burly ( white ) Scotsman serving the food in a very unsympathetic way. Another hotel restaurant closed its kitchens at 9 pm in Dundee ( The George! )
I used to travel a lot with my work for the BBC and Scotland, whilst having wonderful countryside and friendly people, was a disaster for food!
Tony
Agile,
Responding to your other post, so quickly, every fromfrom England I meet in Scotland, even if they've lived here 30 plus years, is still a proud Englishman, and I'm pretty sure the same applies to a Scot south of the border...
As for spending too much time visiting old relatives... well, that matbe a cultural thing.... its not just live relatives... who are very very important... but also dead ones... graves... then, there is the food bit you mention... just can't get authentic "motherland" food here... hell, half the things you find on menus on any "authentic ethnic" restaurant in the UK don't even exist in their places of origin... back 15 yrs ago, as a student in edinburgh, there was a very good take away on the Bridges called Kebab Mahal, though when I went there last yr, the place wasn't really as good as I had remembered it to be (btw, I've not lived in Scotland for the last 15 yrs, was here as a student, graduated, left, worked here and there, and now been here for about 3 yrs as a transient, maybe another year and then I'm away again, so, you see, motherland will always be important)
Right, about the boiler, still a day to go before I make up my mind!!!
Responding to your other post, so quickly, every fromfrom England I meet in Scotland, even if they've lived here 30 plus years, is still a proud Englishman, and I'm pretty sure the same applies to a Scot south of the border...
As for spending too much time visiting old relatives... well, that matbe a cultural thing.... its not just live relatives... who are very very important... but also dead ones... graves... then, there is the food bit you mention... just can't get authentic "motherland" food here... hell, half the things you find on menus on any "authentic ethnic" restaurant in the UK don't even exist in their places of origin... back 15 yrs ago, as a student in edinburgh, there was a very good take away on the Bridges called Kebab Mahal, though when I went there last yr, the place wasn't really as good as I had remembered it to be (btw, I've not lived in Scotland for the last 15 yrs, was here as a student, graduated, left, worked here and there, and now been here for about 3 yrs as a transient, maybe another year and then I'm away again, so, you see, motherland will always be important)
Right, about the boiler, still a day to go before I make up my mind!!!
Rather surprisingly to me there was a phone in on BBC R4 where children of English parents who lived in Scotland were bullied in school just because their family were English and more seriously some younger people were seriously attacked because they were English!
To give some balance, I have never had any problem in Scotland, and have found almost everyone I met charming, friendly and very hospitable. But I have stayed clear of Glasgow and used to tend to stop in Alexandria where the local Indian was not that bad! I have never had any good chinese food in Scotland and now would never eat it except in London, Birmingham. Manchester, Liverpool or Cardiff.
I am looking forward to the Burns night dinner in three weeks time!
Tony
To give some balance, I have never had any problem in Scotland, and have found almost everyone I met charming, friendly and very hospitable. But I have stayed clear of Glasgow and used to tend to stop in Alexandria where the local Indian was not that bad! I have never had any good chinese food in Scotland and now would never eat it except in London, Birmingham. Manchester, Liverpool or Cardiff.
I am looking forward to the Burns night dinner in three weeks time!
Tony
No, I haven't fallen into any trap. I agree that, if loft insulation is installed the OP will only need a 22-24kW boiler. However the situation is now urgent and there is no way of knowing how quickly B&Q will come along to install the insulation. So you have to base the size on the current situation. You therefore install a 30kW boiler (price difference is relatively small) and down rate it to 24kW when the insulation is installed. I am sure the OP would rather have his house warm while waiting for the insulation.
As for the question of cavity insulation, have you asked any neighbours with similar houses if they have had it done? It seems very strange that a 1960's built house with a cavity wall cannot take cavity insulation.
I understand your reluctance to for getting quotes from new firms for a different brand of boiler; though it might be worth asking the present contenders if they have fitted Remeha's and what they think of them.
I have to totally disagree with you there!
You are saying fit a 30 kW boiler, have the loft insulation fitted in two weeks time and spend the next 10 years with an oversized boiler costing more to run!
The clearly only sensible solution is to fit the correct boiler size which will be needed when the loft is insulated ( two weeks ) and then spend 10 years reaping the economy of a correctly sized boiler!
Tony
You are saying fit a 30 kW boiler, have the loft insulation fitted in two weeks time and spend the next 10 years with an oversized boiler costing more to run!
The clearly only sensible solution is to fit the correct boiler size which will be needed when the loft is insulated ( two weeks ) and then spend 10 years reaping the economy of a correctly sized boiler!
Tony
Agile:
I believe, (and correct me if I'm wrong), that modern combi's have a fairly large turndown, and the heating output can be ranged from 24 to 35 kW for instance. So, I don't think I'll be over paying for gas. As D_Hailsham points out, I can have it ranged down later.
B&Q give a range of upto 8-10 weeks for installation, following the survey of the property which is yet to take place!!!. They generally sub-contract it to local installers, so, I guess B&Q jobs don't get any priority, since I paid for it online on the 23rd of December and am still to get a phone call to arrange the survey!!!!, and since I don't know who the subcontractor is, can't even call to give them a nudge!!
Will go round to the neighbours and ask if they have had ant cavity insulation installed.
I believe, (and correct me if I'm wrong), that modern combi's have a fairly large turndown, and the heating output can be ranged from 24 to 35 kW for instance. So, I don't think I'll be over paying for gas. As D_Hailsham points out, I can have it ranged down later.
B&Q give a range of upto 8-10 weeks for installation, following the survey of the property which is yet to take place!!!. They generally sub-contract it to local installers, so, I guess B&Q jobs don't get any priority, since I paid for it online on the 23rd of December and am still to get a phone call to arrange the survey!!!!, and since I don't know who the subcontractor is, can't even call to give them a nudge!!
Will go round to the neighbours and ask if they have had ant cavity insulation installed.
Most boilers will modulate down to about a third of their maximum power.
That may sound OK to you but the problem is that a 37 kW boiler typically only goes down to about 12 kW and thats more than most heating systems usually need for 95% of the year.
The boiler then has to on/off modulate which is not so efficient. Its one of the problems of a high powered combi which is specified for DHW output.
Thats part of the reason my recommendation is that you get a system boiler and keep a cylinder.
Loft insulation is VERY easy to fit yourself and would take about 2-4 hours on an average loft.
Tony
That may sound OK to you but the problem is that a 37 kW boiler typically only goes down to about 12 kW and thats more than most heating systems usually need for 95% of the year.
The boiler then has to on/off modulate which is not so efficient. Its one of the problems of a high powered combi which is specified for DHW output.
Thats part of the reason my recommendation is that you get a system boiler and keep a cylinder.
Loft insulation is VERY easy to fit yourself and would take about 2-4 hours on an average loft.
Tony
Agile";p="1458198 said:
The reality is that the OP is already confused and does not know what he is best served with.
He thought that the BG man would be a heating engineer rather than a salesman!
Anyone specifying a combi without measuring the dynamic flow rate of the mains is potentially heading for a disaster.
As far as we are advised, no one has yet measured this! I take the view that anyone visiting is a nupty if they talk about a combi without measuring the flow rate.
I like my customers to be totally happy with anything I specify or install. Two showers from 15 li/min is too close to the limit in my view and what about when someone uses the kitchen sink or hand basin in the cloakroom at the same time?
Tony
He thought that the BG man would be a heating engineer rather than a salesman!
Anyone specifying a combi without measuring the dynamic flow rate of the mains is potentially heading for a disaster.
As far as we are advised, no one has yet measured this! I take the view that anyone visiting is a nupty if they talk about a combi without measuring the flow rate.
I like my customers to be totally happy with anything I specify or install. Two showers from 15 li/min is too close to the limit in my view and what about when someone uses the kitchen sink or hand basin in the cloakroom at the same time?
Tony
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