Heating System Spec for Office

[thescullster]

Hi all

OK tenuous for DIY, but I am looking to produce an upgrade spec for our office heating.

Building is 17m square with ground and first floors. Each floor is majority open plan with two or three internally partitioned offices/rooms on each floor.

The current system has a gas boiler with Y-Plan (yes just one thermostat for the whole building on the first floor). Hot water is via indirect cylinder.

So far the considerations I have are:

Replace boiler with combi Replace all radiators ? most are rusting and/or have seized bleed nipples (replacements to have dedicated bleed fitting, not a tapping into the radiator panel as existing models); adjust radiator size/position to ensure access to trvs. Replace all thermostatic rad valves Replace all lock shield rad valves Split system to dual zone heating (upstairs and downstairs separated) Install dual thermostats one upstairs one downstairs Install Magna Clean or similar filter Power flush all heating piping Pressure test system prior to commissioning

To determine?

Recommendations for:

Boiler (Worcester, Viessmann?) Radiators TRVs Lock Shields Thermostats (wired or wireless?)

Have I missed anything crucial here? Anyone have recommendations on the hardware to be used. I would not be wanting to go cheap. The company has been using these premises since

1992, so hope it will be a long term investment.

Thanks

Phil

[Theo]

What is your current heating demand at the moment? (boiler kW / annual kWh)

What's your level of insulation? Could it be improved?

If this is a long term investment I'd look into heat pumps, since gas will eventually be phased out and probably become increasingly expensive. Since you're doing a full system replacement you can match the heat emitters to the heating system. Running costs would be roughly on par with a gas boiler (depending on your tariff and the way the market moves).

In particular you might think about what cooling requirements are going to be needed in future. For example many offices are pretty uninhabitable in peak summer conditions, and so an air-to-air heat pump (ie air conditioning

• heating) would handle both needs. Result is happier employees in the summer months.

You'd need to mount some fan boxes on the outside or roof (like traditional aircon units) - do you have space for those?

In the domestic environment the government has been pushing air-to-water air source heat pumps, and the grants are focused that way. In commercial heating there was the non-domestic RHI which has just ended, but air2air or air2water+fan coils could make more sense as they handle cooling as well, and ducting could be easier than radiators (especially in industrial buildings).

Costs rather depend on your current heating demand but air2air could be easier to fit than a water system and save costs that way. Or a small air2water unit just for the hot water tank and air2air for the rest.

Theo

[thescullster]

Thanks Theo

I will have to look into this lot. Are the options you suggest on a par with CH upgrade or a factor or two higher for the size/type of building specified? We currently have hot and cold air-con, but do not intend to use this for heating while the Covid threat is high.

Not sure on the insulation front as the loft is fully boarded and use for storage. Could probably find room for more external fans.

Whilst we would want a reasonable return on the heating costs, it is unlikely that we would get approval for huge expenditure. The arrangement is a little strange, as we rent the building, but at a lower rate as we carry out much of the mainenance/improvements.

Phil

[Andrew]

What's the insulation like ?. If built before 1992 then probably effectively none.

[Owain Lastname]

Depending on where the hot water is required relative to the boiler, that could be wasteful in both heat and water if staff are running washbasin taps all the time. Also a cylinder with an immersion provides a backup. Most workplaces MUST have hot water for handwashing. Consider a pumped return on the hot water loop to reduce delays in drawing off hot water, and legionella and anti-scald valves.

Tamperproof :)

Consider occupancy sensors in offices and other locations.

Owain

[Theo]

It's hard to say without any clue what your current heating demands are. The cost base is a bit different: once you have 'a' gas boiler, it costs relatively little to increase the combustion, up until you need to go to a bigger unit (pipes, etc). The result of this is heating engineers are often lazy and overspec the installation, rather than calculating what you actually need.

ASHPs typically have a more linear cost with heating demand - you have to go from one to multiple fans, etc. I'm not familiar with the market at the large end, especially not the air to air market, to have any idea what costs actually are (as opposed to the fog put about by installers inflating costs due to having grants). It's possible to hit up some prices on webshops, but note that installers are typically not buying from them so the likes of Wolesley aren't actually shifting many and the prices may not be representative.

Does your hot aircon use the heat pump, or is it just resistive heat? Is it classic split unit aircon (refrigerant piping going to a fan unit on the wall or ceiling) or ducted in the roof space?

In a post-covid world it might be worth thinking about MVHR units - they exhaust stuffy indoor air, transferring the heat to fresh air from outside. If one of those were put in the inlet of an ASHP/aircon fan coil you'd get warm fresh air rather than recycling everyone's germs.

Again it's not an area I have expertise in - the BuildHub forum might be a place to ask (MVHR is becoming more popular in selfbuilds).

It's worth looking at because money you spend on insulation will save you money on bills every single year, so you pay once and get a return forever, with minimal loss of performance. Whereas capital costs on heating plant are something you pay upfront but get no return on them (beyond heating the building).

Capex v opex is a tricky one - sometimes it can be hard to get approval for things that will save money in the long run. OTOH sometimes capex projects are easier to do when opex budgets are squeezed.

Theo

[Vir Campestris]

Our place is all done with heat pumps. Most of the time we're pumping heat out - we have a lot of electronics - but in the winter the pumps are pulling heat in.

The cold/hot is distributed by air ducts, all run above the false ceilings, and with matching sets to pull the stale air back out.

No radiators at all. We _can_ open the windows, but there's not a lot of point. Even for COVID.

No idea how the hot water is done.

Andy

[Max Demian]

Why is hot water needed for handwashing? I know that chemical processes (like washing) are faster at higher temperatures, but if you have liquid soap (at room temperature), the water is just for rinsing (which is a mechanical process, not chemical).

Of course, it's *nicer* to have hot water.

[Vir Campestris]

I thought it helped, but since Unicef, the CDC and Yale all say cold is fine...

Andy

[Owain Lastname]

Offices, Shops and Railway Premises Act 1963

10 Washing facilities. (1)There shall, in the case of premises to which this Act applies, be provided, at places conveniently accessible to the persons employed to work in the premises, suitable and sufficient washing facilities, including a supply of clean, running hot and cold or warm water and, in addition, soap and clean towels or other suitable means of cleaning or drying.

The Workplace (Health, Safety and Welfare) Regulations 1992

21 (2) washing facilities shall not be suitable unless? (a)they are provided in the immediate vicinity of every sanitary convenience, whether or not provided elsewhere as well; (c)they include a supply of clean hot and cold, or warm, water (which shall be running water so far as is practicable);

There are some exemptions such as welfare vehicles where a hand-cleaning solution can be provided instead of running water, but they won't apply to almost any building.

and that encourages people to wash their hands, which reduces the risk anything you touch is covered with other people's bodily fluids.

Owain

[Owain Lastname]

is that just for washing the covid off, or all dirt?

Owain

[The Natural Philosopher]

Water that has been over 60°C is essentially sterile. Hot water dries faster in a cold climate.

[Vir Campestris]

Dirt in general.

I think the encouragement because warm is nicer is a good reason though.

Andy

[Chris Bacon]

Go green and get rid of gas. Look to see if there are any incentives. If there are not right now, see if you can hang on until end Sept.