boiler advice please

[king of pipes]

Any pictures it would be most helpful the guys are guessing alot here ? the mix of underfloor and radiator circuits, a primary circuit with a system boiler? The pump is just not man enough, I would say your looking at a low loss header install here it separates each circuit and adds a pump and control valve to each for time and temperature control saving you a fortune in fuel costs , I can see your installers point two boilers for winter use to supply full load heating and hot water then 1 boiler for primary load in the summer for hot water use, personally the quote is reasonable if not a bit underpriced if it includes all the electrical work involved as you will need a bespoke control panel to allow pumps and valves to operate independently and fire the boilers when called for this is a costly exercise but if carried out correctly there are saving to be made . Regards Kop

 

[Glasgow Summer Heat]

Any pictures it would be most helpful the guys are guessing alot here ? the mix of underfloor and radiator circuits, a primary circuit with a system boiler? The pump is just not man enough, I would say your looking at a low loss header install here it separates each circuit and adds a pump and control valve to each for time and temperature control saving you a fortune in fuel costs , I can see your installers point two boilers for winter use to supply full load heating and hot water then 1 boiler for primary load in the summer for hot water use, personally the quote is reasonable if not a bit underpriced if it includes all the electrical work involved as you will need a bespoke control panel to allow pumps and valves to operate independently and fire the boilers when called for this is a costly exercise but if carried out correctly there are saving to be made . Regards Kop

Hi Kop,
Your advice is much appreciated.
I got a bit more info. He confirmed I have a pipe system (return and flow). I asked him if he can keep the price down and he has come back recommending a bigger boiler if going for one boiler..
1. Baxi megaflow 32
2. Horizontal flue
3. 40 KW low loss header
4. Grunfos UPS 2 25-80 pump
5. modifying all the existing pipe work
6. wiring into existing system (I have google nest)
7. Balancing new radiators
He has quoted £3055 including VAT.
Do you think this is reasonable? When I looked at the price of the boiler, low loss header, pump and the flu it is probably about £1500..unless I am missing something which is the likely case?

Do you see any advantage to go for 2 smaller boiler (£1200 more expensive) rather than this new quote for a bigger boiler?

Thanks again folks.

 

[king of pipes]

As I said before its a bit underpriced in my opinion but we are not 100% sure what you are getting ? if done properly there's other parts needed , Google nest will only control 1 heating circuit and the hotwater primary circuit , what about the underfloor circuit ? Another nest thermostat ? your fuel costs are expensive and worse still your property is still cold 20 °c your existing boiler is possibly never modulating down or switching off I would be a careful here you could be end up in the same situation a cheaper job will mean a sacrifice somewhere please tread carefully. Kop

 

[Glasgow Summer Heat]

As I said before its a bit underpriced in my opinion but we are not 100% sure what you are getting ? if done properly there's other parts needed , Google nest will only control 1 heating circuit and the hotwater primary circuit , what about the underfloor circuit ? Another nest thermostat ? your fuel costs are expensive and worse still your property is still cold 20 °c your existing boiler is possibly never modulating down or switching off I would be a careful here you could be end up in the same situation a cheaper job will mean a sacrifice somewhere please tread carefully. Kop

I only have one thermostat for google nest.
The underfloor heating is in the Garden room (5 by 4 meter. It was done by a builder 15 years ago and was done very poorly. As far as we can figure out it is just configured as another radiator without any manifold!
I really want to get it right this time as have spend lots of money in the past and has made little difference. Happy to pay more but get it right this time.
What other things do you think I should ask him to do?
The underfloor heating is titled and it would be a major job involving taking all the tiles and floor boards off.
Thank you
S

 

[SimonG]

No pump or manifold for the underfloor heating then. Not surprised the poor old pump cant cope.

Might be worth getting a manifold and pump for the underfloor heating so its properly controlled.

I would try that first and then see how the system performs.

 

[gmartine]

Get some more quotes preferably from engineers with a knowledge of integrating UFH in large systems by using hydronic separation (CCT's or LLH) especially if you want to continue to use the garden room. We suspect that trying to heat your conservatory in conjunction with the rest of the house is probably at the root of your problems unless you have a systemic design flaw elsewhere. Just curious, is it a room that is in much use because it's the first room I'd turn off if I had your scale of fuel bills especially as it is likely to be very poorly insulated.

Personally I'd go to the Viessmann site and get a quote or two from an authorised installer, unless you live in a massive house with very little insulation you really shouldn't need two boilers. A large boiler with weather comp properly set up should give you the results you desire but it won't be cheap. As you've already said you've already spent a lot with unsatisfactory results and if you keep chasing the price down you'll attract those engineers that'll give you exactly what they think you want which is price over performance.

 

[king of pipes]

Get some more quotes preferably from engineers with a knowledge of integrating UFH in large systems by using hydronic separation (CCT's or LLH) especially if you want to continue to use the garden room. We suspect that trying to heat your conservatory in conjunction with the rest of the house is probably at the root of your problems unless you have a systemic design flaw elsewhere. Just curious, is it a room that is in much use because it's the first room I'd turn off if I had your scale of fuel bills especially as it is likely to be very poorly insulated.

Personally I'd go to the Viessmann site and get a quote or two from an authorised installer, unless you live in a massive house with very little insulation you really shouldn't need two boilers. A large boiler with weather comp properly set up should give you the results you desire but it won't be cheap. As you've already said you've already spent a lot with unsatisfactory results and if you keep chasing the price down you'll attract those engineers that'll give you exactly what they think you want which is price over performance.

Very wise words there mate !
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I think you need a couple more estimates there maybe a engineer on here post the job and see if anyone responds. Best of luck kop 👍

 

[siricosm]

Another option you might consider is to add a buffer cylinder to your system, if you have space, perhaps in your boiler room? The boiler would heat the cylinder and be controlled by a cylinder stat. Then since you have TRVs on all the rads you can use a smart pump and leave it on all the time during the heating season. When the TRVs all close it will throttle down, and when they open it pump more.

This would solve several issues. You could then run a larger pump, if that is really needed. Your balancing problem would be greatly reduced, as the TRVs would also act to balance the system. What will happen is that all the rads will reach the temperature required to maintain the heat setting in each room and they will stay at that temperature whether the boiler is on or not. You also don't need to worry about zoning, and you could control the underfloor area with a remote TRV.

It is also pretty cheap. All the work in the boiler room, and maybe 500 hundred pounds for a small cylinder, possibly larger expansion vessel, a smart pump and remote TRV.