Boiler choices.

getmore4less

Looking like our 25y+ Prima 50f is going to need money spending or get replaced.

At that age not sure it won't become a money pit if we fix it

Getting 1st quote for both, from the guy that checked it out.

Need to do some boiler research to look at trade offs

Guess for a starter, consider and avoid.
Don't mind putting a bit more in to get better as a lot is install cost.

Then compare against their preferred choice and other quotes.

System boiler for heating and tank via 3way mid pos valve.

dual temp probably needed to get condensing when only heating but hotter for water , do they all support that?

Current boiler has had no problems getting house to temp even when very cold after being away.
Think we can look at similar output.

Programmable stat(time, temp) for both.
Would like to keep that ability, variable temp on water was rare when I put this OWL controller

Unlikely we will be adding need for more capacity  or suplimenting with alternatives like solar in the near term.

ThisIsWeird

Cannot comment on makes to go for, but your current jobbie would appear to have a 15kW output - that's a pretty common size, so a whole world of replacements.

This could be a straight swap, although your new boiler will need a condensate pipe running to either an internal drain, or to a suitable exterior location.

But, things I think worth considering. Your existing boiler is presumably 'vented', and has a small F&E tank in the loft? I would personally look to change this to a 'system' boiler, the only difference being that it's 'sealed', loses the small tank in t'loft, and it has a pressure gauge for you to look at. Just less 'water' all around, and less to go wrong in a wet way.

Future-proofing - make sure it's H2 compatible, tho' I suspect all new boilers will be? 

Seriously consider changing the 3-port 'mid' valve you have to two 2-porters. Ie, from a Y to an S (say that, and the plumbers will think you are gawd). Just more effective and efficient; your two demands - CH and DHW - will have full autonomy.

And more seriously consider 'Smart' controls, ideally with a system to match your new boiler for the best possible efficiency. There's 'Opentherm' and another with a funnier name. Basically, it means that the room sensor will give fine control to the boiler, not just telling it to 'shut off' when the house temp has been reached, but things like, "I'm getting close - ease off, now. A bit more. Steady as she goes. Nice! Keep it there, aaaaaannndd....OFF!" sort of thing.

And, 'weather compensation' - an outdoor sensor that will turn your boiler up and down according to actual need. This will/should keep your boiler running at the coolest level it can get away with to keep your house warm. The cooler the boiler heats the water to, the more efficient.

And, if you do need to change any radiators - especially in the main 'living' areas - increase their 'size', ie output. Go for extra fins, or even an extra physical size, or add a second rad. This will give you the same output as before, but on a lower water temp = efficiency and savings.

BUFF

ThisIsWeird said:

And more seriously consider 'Smart' controls, ideally with a system to match your new boiler for the best possible efficiency. There's 'Opentherm' and another with a funnier name. Basically, it means that the room sensor will give fine control to the boiler, not just telling it to 'shut off' when the house temp has been reached, but things like, "I'm getting close - ease off, now. A bit more. Steady as she goes. Nice! Keep it there, aaaaaannndd....OFF!" sort of thing.

And, 'weather compensation' - an outdoor sensor that will turn your boiler up and down according to actual need. This will/should keep your boiler running at the coolest level it can get away with to keep your house warm. The cooler the boiler heats the water to, the more efficient.

And, if you do need to change any radiators - especially in the main 'living' areas - increase their 'size', ie output. Go for extra fins, or even an extra physical size, or add a second rad. This will give you the same output as before, but on a lower water temp = efficiency and savings.

Opentherm is a (supposedly common/open/transparent but not always ...) communications protocol between the boiler & the programmer/room 'stat allowing them to take over (as ThisIsWeird  says) for finer control of boiler modulation (tailoring output to demand).
Some manufacturers such as Vaillant, Viessmann & Worcester Bosch have equivalent but proprietary protocols - if you buy one of their boilers I would recommend to use their own controls. At least in the case of WB (& possibly the others) if installed at the same time as the boiler they may be warrantied for the same length as the boiler (potentially up to 12 years subject to usual T&Cs like annual servicing).

jennifernil

I can suggest a Viessmann Vitodens as we had one fitted some 7/8 months back and are very pleased with its performance.  We have a 100 model, heat only, HW  vented  cylinder, with 2 pumps in the system.     We have a 12 year warranty.

Recently fitted tado controls with smart TRVs on most radiators , pleased with that too.

getmore4less

Thanks,

Straight swap should be possible as boiler is in garage outside wall with suitable drain for a condensate run.rk central.

Pump, tank, etc are all in a cupboard in the middle of the upstairs not sure we want disruption there.

The Owl "smart" does some weather compensation, with warm up and cool down times to hit target temp/time seemed to be working.

That is something we could improve with boiler modulation.

I like the ability to have multitiple tank temp/times which was hard to find with most controls at that time

No TRV currently,  initial quote says these needed for bedrooms?
Suggest a read of building/heating regs is needed.

Would prefer smart TRV to get temp/time profile for used rooms.
Getting into some home automation so would want support for something in the likes of home assistant as well as any standalone ecosystem.

Got some(lots) reading to do.

Rad's seem to be ok for size in most rooms, most are type 22.

Probably a phase 2 review if we can't get the house warm with lower boiler temps.

Lounge/diner has 2+1  that overheats with  stat in hall/stairs rad there maybe a bit under but we do have two rooms upstairs we don't use it has a bit more work to do than if those rooms were heated.

With more clothes and a bit of help from a 1kw fan heater we have been surviving at 15c-18c in main room.

Got some portable temp/humidity to start monitoring in Nov

When the heating was on.
main room would range 17c-23c(too warm)
stat in hall(19c) 16c-20c(comfortable but could be lower)

Scope to make some temp reductions better balance to get savings.

ThisIsWeird

Smart TRVs in bedrooms and other 'occasional' rooms - definitely, I'd say.

If rads are 22's, there's little opportunity for upsizing without going physically large. Likely not worth it, espec for bedrooms.

Not sure what you are saying about lounge/dining, 'overheats' or 'a bit under'? Def the one to try and oversize if poss, as it's the area most used, so more consumptive of gas. If you can heat that room with the boiler flow at, say, 50-odd degrees, your boiler will be running at near max efficiency. 

Smart room stat relocated to lounge, and no TRVs in there. TRV on hall rads instead.

15o is chilly. 18o is perfectly acceptable for most folk with an extra layer of clothes, or a blanket over t'knees. It should be stable, tho', as even 1 degree fluctuations are unpleasant and uncomfortable.

Try and leave the leccy heater alone - X3 cost! And don't you find fan heaters are morish - once off, you feel it right away, so prob want it back on asap? If you must, an oil-filled should provide a more level and stable output - if really needed.

What type of hall stat do you have? Wireless? If so, try moving it to the living area to stabilise the temp in there - the most important place. Manually adjust hallway rad to just provide background heating, or even off if you want. All other rads on frost until needed. If hall stat is wired so not so easy to move, then - depending on how long you'll be stuck with the existing system - it might be worth buying a cheap or second-user wireless stat so you can still move it to the sitting room; receiver fits on wall where old stat is, and wireless stat unit goes in sitting rm. That should sort your fluctuating temps (uncomf and costly) and use of leccy! Look carefully on t'Bay and you'll likely pick up a 'smart' type for not much - so easy to control, and you resell it when new system installed.

ThisIsWeird

getmore4less said:

1) Pump, tank, etc are all in a cupboard in the middle of the upstairs not sure we want disruption there.

2) The Owl "smart" does some weather compensation, with warm up and cool down times to hit target temp/time seemed to be working.

3) I like the ability to have multitiple tank temp/times which was hard to find with most controls at that time

1) The change from a single 3-porter to two 2-port valves, and going from vented (wee F&E tank) to unvented, are not essential by any means. Just 'better' imo, and not at all disruptive. Little chaos to be caused in the airing cupboard. I'd certainly ask any quoting plumbers for their views?

2) Not familiar with Owl, but assume it modifies the heating start time based on how cold the house is? So, yes, that's temp/weather compensation. Whether having an external temp sensor - that's what 'weather comp' used to be - is better, I don't know, but suspect it might be. The idea is to always have the boiler's flow as low as possible, whilst still being high enough to heat the house. You can do this manually - turning the boiler's output control down when you can, but back up during cold snaps - but that's a chore, and most folk wouldn't bother except for perhaps a few times a year - clearly a waste of max efficiency. If, instead, an external sensor tells the boiler to increase/decrease the flow temp on a real-time basis, the boiler should - theoretically - always be running as cool as possible.

3) Any new Smart controls should give you easy-to-use control over CH & DHW timings, and room temps. If you are saying that you also want control over the DHW cylinder temp, that's a different matter, and would clearly require an electronic temp sensor on the cylinder (as opposed to the normal cylinder 'stat), coupled with controls that will allow this. Wireless cylinder stats certainly exist, but I have no idea about whether this also allows changes in temp - but surely some will? Of course, there then may be the added issue of Legionnaire's.

getmore4less

Our owl uses web based outside temp not as good as a local outside sensor but did work to decide when to put on the heating to hit temp/time.
It also has a tank temp sensor that can be used to program the DHW 
In effect it is just a 2 zone system where one is the tank.

FreeBear

getmore4less said: Straight swap should be possible as boiler is in garage outside wall with suitable drain for a condensate run.rk central.

Getting into some home automation so would want support for something in the likes of home assistant as well as any standalone ecosystem.

Rad's seem to be ok for size in most rooms, most are type 22.

Be careful putting a boiler in the garage - These spaces can get cold & damp which doesn't do the electronics any favours. Many manufacturers do not recommend installing a boiler in an outbuilding (which what a garage is).

Home Assistant is fun, but it can be a rabbit hole you disappear down without an exit. I'm adding a bunch more sensors to my HA and am waiting on some mains powered ESP32 modules to arrive.

Radiators - You can get Type 33, but these are huge even compared to Type 22 radiators. Ideally, with a modern condensing boiler, having radiators 25-50% oversized will allow you to get the best out of them with lower flow temperatures. It would also put you in the position of being heat pump ready if/when the time comes. In the meantime, whack in as much insulation as you can and kill those draughts.

getmore4less

ThisIsWeird said:

Smart TRVs in bedrooms and other 'occasional' rooms - definitely, I'd say.

If rads are 22's, there's little opportunity for upsizing without going physically large. Likely not worth it, espec for bedrooms.

Not sure what you are saying about lounge/dining, 'overheats' or 'a bit under'? Def the one to try and oversize if poss, as it's the area most used, so more consumptive of gas. If you can heat that room with the boiler flow at, say, 50-odd degrees, your boiler will be running at near max efficiency. 

Smart room stat relocated to lounge, and no TRVs in there. TRV on hall rads instead.

15o is chilly. 18o is perfectly acceptable for most folk with an extra layer of clothes, or a blanket over t'knees. It should be stable, tho', as even 1 degree fluctuations are unpleasant and uncomfortable.

Try and leave the leccy heater alone - X3 cost! And don't you find fan heaters are morish - once off, you feel it right away, so prob want it back on asap? If you must, an oil-filled should provide a more level and stable output - if really needed.

What type of hall stat do you have? Wireless? If so, try moving it to the living area to stabilise the temp in there - the most important place. Manually adjust hallway rad to just provide background heating, or even off if you want. All other rads on frost until needed. If hall stat is wired so not so easy to move, then - depending on how long you'll be stuck with the existing system - it might be worth buying a cheap or second-user wireless stat so you can still move it to the sitting room; receiver fits on wall where old stat is, and wireless stat unit goes in sitting rm. That should sort your fluctuating temps (uncomf and costly) and use of leccy! Look carefully on t'Bay and you'll likely pick up a 'smart' type for not much - so easy to control, and you resell it when new system installed.

The fan heater is just while our boiler it out of action till the new one gets picked and installed.
Been sitting in the garage for over 25y just in case it's probably 40y old.
Takes the chill of the room in the morning and evening we go out most days for a few hours.
1kw(not 2kw) setting, low fan, thermostat stops it getting too warm or moreish.

When it was working... 
We do have a balance problem, the programable stat(wired) in the hall is set to 0.3c hysteresis and keeps steady temp but that causes the living room to creep up slowly(no big swings), until one of us goes for a pee then the hall gets a boost.
lowering the hall stat was work in progress.
Might be time to ditch the owl system and move on.
 

Priority is get a new boiler that gives us heat and options

First quote £3,200(inc vat), Ideal max 2 heat (quote needs fleshing out with detail like which TRVs) 
From reading other threads that seems to be on the high side for a swap with just essential changes. 

jennifernil

Our new Viessmann replaced a 34 year old Potterton, which was still working fine but was not particularly efficient, so with the current cost of gas we decided it was time to swap.  The new boiler is the largest model of heat only ones as we have a large house to heat.

Our quote was £3000 for a straight swap, magnetic filter, 2 new pumps, and upgrade of gas pipework from meter to boiler.     We already had a fairly new timer for CH and  HW,  cylinder stat, frost stats, and TRVs everywhere, so continued with those until we decided which smart system to go for.

We have just last week swapped 12 of the 18 regular  TRVs for smart ones, leaving less often  used rooms with the regular ones, and control things via the smart TRVs, setting a schedule and temperature for each room that has them.  HW is also on a schedule, but water temperature is via existing cylinder stat.

Still tweaking times and temperatures to see what works best for us, and discovering what other features the system offers, it is a steep learning curve!